Dread Fury and d100 Combat

Happy the blest ages that knew not the dread fury of those devilish engines of artillery, whose inventor I am persuaded is in hell receiving the reward of his diabolical invention, by which he made it easy for a base and cowardly arm to take the life of a gallant gentleman; and that, when he knows not how or whence, in the height of the ardour and enthusiasm that fire and animate brave hearts, there should come some random bullet, discharged perhaps by one who fled in terror at the flash when he fired off his accursed machine, which in an instant puts an end to the projects and cuts off the life of one who deserved to live for ages to come.

Don Quixote by Miguel de Cervantes

Continuing my posts on building a d100 game system for an upcoming fantasy Renaissance campaign. The focus here is combat, and mundane weapons and armour (I will get to magic in a future post). Starting with a bit of combat philosophy, I will look at damage and how it is mitigated by active and passive defences, initiative, and actions in combat. I will end with my design choices so far.

What is Combat in Roleplaying Games Anyway?

There have been conflict resolution procedures in most roleplaying games, starting from the first edition of D&D. Because combat involves chance and opposing wills, its outcomes are uncertain, so combat can take the game in unexpected directions. Which is part of playing to find out what happens.

One framing for combat in roleplaying games is Combat as Sport versus Combat as War, where combat as sport might be a “fair fight”, and combat as war has a much more adversarial relationship between players and GM, where all sides seek asymmetric advantages to win at minimal cost (just as you would in the real world). I will add another axis to this, labeling one end of this axis “Combat as Fail State”, and the other end “Combat as Speed Bump”. Speed Bump combat is a combat that you power through in as few dice rolls as possible – maybe only one roll, in order to get back to whatever the game is focused on. Combat as fail state means that gameplay seeks to avoid combat at all costs, as the risk of character mortality is so high.

A quick diagram and some contestable examples. The closer you are to the point where the X and Y axis overlap, the more time the game system devotes to combat as the default mode of play.

Different groups of players will have different preferences for what they want in combat. Different games or campaigns can also have different expectations set in session zero. For a Night’s Black Agent’s campaign, I promised my players boss fights, but I did not promise that they would survive them.

For a d100 renaissance game with gunpowder weapons, I think a key design consideration is how lethal firearms will be in the setting and rule system. On the whole I think that combat is an expected element in most d100 games, and they fall more at the realistic Combat as War side of the graph. This may be due to the early Runequest (RQ) combat rules being derived in part from the authors experience of medieval reenactment combat in the Society of Creative Anachronism. It is a lot harder to think of hit points (HP) as plot armour when the rules say your character took a critical hit to the head. So you get a more visceral feeling as you play, unlike in D&D where you can feel immune from consequences due to HP bloat.

Damage, Special Damage, and Wounds

I will compare and contrast a few different d100 games, splitting them up into chunks. These are of necessity, brief descriptions of rules that often detailed at length in game books, so many of the quirks and subtleties of each system will be glossed over:

• Runequest 2 (1978): A hit means you roll weapon damage, and hit location, then subtract a fixed number for armour worn in the location from the damage roll. A PC has both general hit points and location hit points. Wounds affect both general and location HP. When general HP drop to zero, the PC is dead. When a specific location reaches 0 HP a character falls (legs), loses use of limb (arm), or has two turns until they die (abdomen, chest, or head). A limb hit for six more points of damage in a single blow is amputated. While this is a bronze age fantasy game, it includes the comment “A modern, high velocity, bullet, hitting a limb hard enough to put it out of action, will probably kill the owner of the limb by hydrostatic shock.” (RQ2 p.20) A critical hit (a roll equal or less than 1/20 of skill) ignores armour, while an impaling hit (a roll equal or less than 1/5 of skill) increases damage (eg a weapon doing d6+1 damage would do 2d6+2 damage).
• Mythras (2016): Retains location HP, but drops general HP. Location HP are a bit higher than in RQ. When you drop below 0 HP in a location, Endurance checks are needed to avoid being disabled (limb) or incapacitated (head, chest, abdomen). The special effect menu has 40+ options you can choose from, but in my experience Choose Location, Bypass Armour, and Maximise Damage are selected 95% of the time by my players. Choose Location is a dominant strategy in special effect selection, as you can choose an already wounded location. This makes Mythras PCs more vulnerable to being quickly knocked out of combat than RQ PCs (an average PC has 4 HP in their arm, so four points of damage there is enough to trigger a karmic death spiral), unless the GM deliberately avoids hard moves against the PCs and has foes attacking in Combat as Sport mode.
• Call of Cthulhu 7E (2014): Retains general hit points, but drops location hit points. A single wound that does less than half HP just reduces your HP score. A wound that does more than max HP in one blow causes death. Anything in between is a major wound, the character falls, must make a CON check to remain conscious, and if reduced to 0 HP is dying. A dying character needs first aid to avoid death. CoC PCs rarely wear substantial armour. An extreme success on an attack causes increased damage. Pulp Cthulhu (2016) doubles HPs and does not have major wounds, but does check to see if they are knocked out if they lose half their HP in one blow.
• Clockwork and Chivalry 2E (2013): Similar to Coc7E, but you can keep fighting below 0 HP if you make a Resistance roll, until you reach negative HP equal to your starting HP score. This potentially doubles your HP, but with more uncertainty than Pulp Cthulhu. Major wounds are more specific than CoC7E, and are determined by rolling on a table, and range from cosmetic scars to temporary incapacity. Major wounds when below 0 HP roll on the Grievous Wound table, which can include instant death outcomes. Armour only provides half protection against guns up to their normal range, but full protection beyond that. Critical hits do maximum damage and ignore armour.
• Delta Green (2016): Damage bonus from STR is a fixed modifier (from -2 to +2) rather than a die. Has general HP and no location HP, and at 1 or 2 HP you are unconscious, at 0 HP you are dead. Any time you are reduced to 2 or fewer HP, you must make a CONx5 test to avoid losing 1d10 from a character stat. A distinctive feature of this game, is the lethality rating for automatic and heavy weapons, where weapons have a 10-30% chance of being instantly fatal if they hit, regardless of HP. If the lethality roll fails, add the dice together to determine HP damage. For example, a heavy sniper rifle has a 20% lethality rating, and where a Rifle does 1d12+2 damage (3-14), the sniper rifle will do 3-20 damage if it does not land a lethal blow.
• Mothership (2022): This game is not an evolution descended from RQ, and is a streamlined game focused on sci-fi horror (and a hefty does of “invisible rules” or assumed GM knowledge on how to run games). A character will have two wounds (three wounds if a combat specialist). Each wound has 10-20 health points. When you lose all of the HP for a wound, you roll on a wound table (different types of weapons have different tables). Armour is ablative, in that any penetrating blow destroys the armour. Armour ranges in value from 1 to 10. Weapons, however, can do anything from 1d10 damage for a Pistol, through to 1d100 damage for a Laser Cutter (which to be fair, is a one shot weapon with a one hour recharge), and some weapons inflict automatic wounds as well (such as 1d5 wounds for a frag grenade, which will kill most characters).
• Basic Roleplaying (2008): A toolkit system like Mythras, by default BRP uses general HP, a major wound system, and PCs stop fighting at 0 HP and take a fatal wound. BRP treats armour differently, by default armour is rolled randomly (the equipment tables retain an option for fixed armour values). This acknowledges that all armour has weak spots (typically at the arm pit, groin, or eye slot on a human), and creates a wider range of damage outcomes.

How many hits can an adventurer take and keep fighting? My own preference is that a PC should be able to survive at least two normal blows, so that they have time to change what they are doing.

Active Defence – Dodge, Parry, Block

One of the dynamic features of d100 games is that they include active defence options, as well as passive defence from armour (and in Mythras, shields). A PC usually has the option to parry with a weapon, to dodge a blow by movement, or to block with a shield. Parrying risks damage to the weapon, which can cause it to break. Dodge only works if the blow can be reasonably avoided – if you are stuck in place, or next to a cliff, or trying to dodge a house sized object, then dodge is unlikely to work. In Mythras, the equivalent to Dodge, Evasion, leaves you prone on the ground, which is only delaying the inevitable.

In CoC7E, you can fight back when attacked. If your roll is better than your foes, they take damage. You do not get bonus damage from extreme success when fighting back.

You have to go to a completely different game, Usagi Yojimbo, to find the classic defence mechanism of taking a few paces back out of range of the enemy.

The problem of shields

Compared to D&D, shields are amazing in d100 games. In RQ2, you could roll to block an attack with your shield, absorbing 8-16 points of damage depending on the size of the shield. One of the effects of increased protection from shields, is to increase the number of rolls between opponents in combat before a decision is reached, which increases the time required to play out a combat scene.

In Mythras for example, a heater shield blocks all damage on a location the shield is blocking, giving the shield. The difference between maille armour (six armour) and articulated plate (eight armour) is only two points. While this reinforces the dominance of the Choose Location effect (to avoid locations covered by the shield), it can make the Sunder effect useful to batter the shield down over several blows. A d10+2 Glaive with average damage of 7.5 a blow would break a six armour/12 HP heater shield in eight blows. In RQG, shields take 1 HP of damage each time a blow penetrates them, so it will take 12 blows to render a medium shield (12 HP) completely ineffective, but that first blow needs to do at least 13 damage.

The problem for a renaissance game, is that in history shields were abandoned as the quality of steel for armour and weapons improved in Europe, and combatants equipped themselves with two-handed weapons.

One solution is to just say that gunpowder weapons ignore all shields. I also like the “Shields shall l be splintered” house rule (you sacrifice a shield to negate all damage from one attack), but that does not make sense for the renaissance buckler shield, which is entirely made of metal, and is more of an aggressive deflecting device than a passive blocker. A roleplaying solution is to just say that people have stopped using shields, so its not an option for PCs.

Passive Defence – Armour

Armour is generally treated as passive damage reduction in most of the d100 games I have examined. The renaissance was a period of incredible change in armour, with older styles being superseded by improved plate armour that was both thicker and made of softer metal in order to be proof against pistol and musket fire. As muskets improved, heavier muskets with larger powder charges could penetrate almost any armour, so even proof armour was mostly abandoned by the mid-17th century in Europe (the Polish Hussars being a notable exception).

Polish Winged Hussar

I am going to look at how three game systems represent the armour worn in the renaissance: Basic Roleplaying (BRP), Mythras, and Clockwork and Chivalry (C&C).

• BRP: Full Plate grants 1d10 Armour Points (AP) or 8 AP in a fixed AP game. Half Plate grants 1d8 AP, or 7 AP. A heavy helmet would add +2 AP. While its not exactly on the list, I think a leather buff coat with lobstertail helmet and a metal breastplate, could be treated could be treated as Hard Leather with a Heavy Helmet for 1d6+2 AP or 4 AP.
• Mythras: Articulated Plate provides 8 AP. Half Plate is 5 AP. A combination of buff coat and plate armour is 3 AP in areas only protected by the buff coat (arms) or leather boots, 8 AP in the head and torso.
• C&C: Full plate grants 5 AP. Half Plate grants 4 AP, and Medium armour (buff coat, breastplate, and lobstertail) grants 3 AP.

Weapons

The Renaissance is also a time of change in weapons – if there was ever an era for a Gygaxian polearm list on the equipment chart, its the Renaissance! Its a feature of the game, rather than a medieval stasis bug, and of course, in a fantasy Renaissance you can make some decisions to mix anachronisms together. There were, however, compelling reasons to adopt gunpowder firearms over traditional longbows and crossbows:

• Muskets were cheaper than military crossbows, which were complex machines
• Deadly wounds could be inflicted at long range against opponents in the best armour
• Logistics was easier – shot can be quickly made in the field and is lighter to carry than arrows
• In siege or urban warfare, a firearm user does not need to expose themselves to return fire
• Less strength or fitness was needed to use a musket
• Materials for muskets and shot were not in short supply (unlike Yew trees in England)
• People preferred shooting them.

One feature of older d100 games, is that the difficulty to learn a weapon was in part handled by requiring a minimum STR and DEX score, eg in BRP a longbow requires STR 11 and DEX 9 to use effectively – in history it was noted that longbows required years of training, constant practice to maintain skill, and good physical condition to loose volleys of arrows in battle (and after a long campaign archer strength might be debilitated by disease). This could be reflected in base skills of varying levels for different weapons. Overall I prefer the Mythras approach of calculating base skill levels (adding two ability scores together) as it generally results in higher minimum skills for PCs.

The transition away from “proof” armour that could stop musket balls, was driven by the physics making it easier to increase the power of muskets, but armour ran into weight limits of what could be worn even by fit, trained, professional soldiers.The problem is that if you just boost the raw damage of firearms, to ensure they penetrate armour, then in any situation where the PCs are not wearing armour, a hit from a firearm will kill them in one shot.

Keeping things simple, I am going to consider only three weapons across three game systems: Basic Roleplaying (BRP), Mythras Firearms Supplement (Mythras), and Clockwork and Chivalry (C&C). The weapons of comparison are the rapier, the flintlock pistol, and the flintlock musket. Remember that weapon damage interacts with character HP, and armour, so while C&C weapons have more damage dice, C&C characters can fight at negative HP. This is very much an apples to oranges comparison.

Rapier

• BRP: 1d6+1+damage bonus damage, base skill 15%, 15 HP for parrying, STR 7 DEX 13 minimum to use.
• Mythras: 1d8 + damage bonus damage, base skill STR+DEX, 5 AP and 8 HP for parrying.
• C&C: 1d8 + damage bonus damage, STR 7 DEX 13 minimum to use.

Flint Lock Pistol

• BRP: 1d6+1 damage, base skill of 20%, one attack every 4 rounds, range of 10, STR 7 DEX 5 minimum to use, and malfunctions on 95-00. The value of primitive/ancient armour is halved against firearms (round up).
• Mythras: 1d8 damage, base skill STR+DEX, four actions to reload (less one with Rapid Reload combat effect, but with a typical PC having three actions you get a faster rate of fire per five second combat round than the other two game systems), range 10/20/50, ignores four points of armour.
• C&C: 1d6+2 damage, Range 5m, 3 rounds to load, STR 9 DEX 7 minimum to use

Flintlock Dueling Pistol (bonus weapon because C&C has a lot of firearms)

• C&C: 2d4+1 damage, range 10m, 2 rounds to load, STR 9 DEX 9 minimum to use.

Flintlock Musket

• BRP: 1d10+4 damage (1d8 as a club), base skill of 25%, one attack every 4 rounds, range of 60, STR 9 DEX 5 minimum to use, and malfunctions on 95-00. The value of primitive/ancient armour is halved against firearms (round up).
• Mythras: 1d10 damage (2d6 as a club), base skill STR+DEX, four actions to reload (less one with Rapid Reload combat effect, but with a typical PC having three actions you get a faster rate of fire per five second combat round than the other systems here), range 15/100/200, ignores five points of armour.
• C&C: 2d8+1 damage (d6 as a club), range 30m, 4 rounds to load, STR 11 DEX 9 minimum to use.

The Apples to Oranges Comparison

So let us compare weapons to armour, against typical HP for a normal (average damage) and a special success (maximum damage), in each system. Assumptions include average HP based on CON 11 and SIZ 13, no melee damage modifier. There are no buffs to attack or defence from magic, nor any use of luck mechanics.

Interpreting the box colours: Green (no damage), Yellow (damaged, but no chance of being knocked out of the fight), Orange (some chance of being knocked out of the fight), Red (almost certainly knocked out of the fight).

BRP Assumption: average armour rolls with heavy helmets (+2).

Assumption: first special effect is choose location Arm, which has 4 HP, second effect for a critical success is either Maximize Damage or Bypass Armour.

Assumption: weapons are at normal range for armour penetration (ie armour is halved).

Now after the gunpowder weapons have been fired, I will look at what the second blow does, with the following assumptions: (1) Pistol switches to Rapier, (2) Musket switches to two-handed club, and (3) the first hit was an ordinary success doing median damage.

The first number is the damage from the first blow, the second number is the damage from the second blow.

Some observations:

• BRP is the most lethal system for the first blow, as its special success results for double damage occur 20% of the time.
• C&C is the least lethal system for the second blow, in part because the Musket does such low damage as a club (d6 compared to 2d6 in Mythras).
• Mythras is the most lethal system for the second strike due to the cumulative impact of injury to a specific location. While it looks like full plate armour can entirely prevent a lethal first strike, if you chose not to go with Choose Location as your first critical success effect, and went with Bypass Armour and Maximize damage, then a pistol hit against an arm knocks a foe out, as does a musket hit against an arm, leg or head location.

Ultimately, I am not happy with any of these three systems. All three are a bit too dangerous to PCs who are expected to fight, and I think my group wants a long term campaign that is closer to “combat as sport” where they do not have to obsess about ensuring min/max combat and survival skills for their PCs. I think my main solution is to go with a general HP/serious wound approach, dropping hit locations, and to then buff HP to a range where all PCs will have 20-30 HP (which also ties in with the desire to use The One Ring journey and fatigue system). A high CON score still remains useful for mitigating serious wounds. I might use a Mothership approach, where gunpowder weapons inflict an automatic serious wound if any damage penetrates the armour, even just 1 HP. Another armour penetration mechanic not used by any of these systems, is the all-or-nothing approach, i.e. any firearm shot that penetrates armour inflicts full damage, with no reduction.

Initiative and the OODA Loop

For an online age, speed of resolution of actions becomes more important, because everything takes longer to resolve online. This is a reason for dumping the Mythras combat effects, or RQ strike ranks, and going for a set process when special or critical hits are scored.

The players want a swashbuckling game, which means the game system needs to allow creative exploits that are dependent on the situation and the environment. Rather than specifying all of these in detail ahead of time, I assume that as an experienced GM I can make judgements as the game progresses, offering fail forward or success with a complication where needed.

While I do find the Fast/Slow initiative/action system in Shadows of the Demon Lord interesting, my key decision here, is to adopt a Dr Who initiative system:

1. Intent – players choose their actions.
2. Talking actions are resolved first – even if its just witty repartee, and not a social skill check.
3. Running moves – this can include the party agreeing to a campaign loss in order to flee the combat with their wounded comrades.
4. Doing moves are resolved – this can include swashbuckling moves, operating machinery, opening or closing doors, or using a utility item such as an alchemical potion.
5. Combat – anything involving attacks and damage is resolved last (eg firing an artillery piece is a combat move, not a Doing move).

If it is not clear from the established narrative who should act first, resolve actions in DEX+INT order.

How Many Actions per Round?

Assuming the five second timescale of most d100 games, my preference is one attack action per player turn, per round of turns, unless some special resource is expended, or PC skills are over 100%. I am not planing on including magic that allows “haste” or multiple actions. The Dr Who system has a stacking penalty for multiple actions and I will have to think about how that plays out in d100 (a -20% cumulative penalty feels okay). Because of the way CoC7E opposed skills work, PCs getting to split their skill for multiple attacks will be rare until they get their skill up to 200%.

Other Design Choices

Fire magic and gunpowder do not play well together. Allowing mages with fire spells to trigger explosions in gunpowder weapons or powder magazines is fun and exciting the first time it happens, and dull as ditch water once it becomes an “I Win” button for all future combat encounters. So the first rule of magic in a game with gunpowder is that no one has fire magic.

After that decision, I think the fundamental call for an era of online play, where three hour sessions have become the norm for my group rather than four hour sessions, is how much time do I want to spend on combat? I think that both the micro-management of Mythras, and attack/dodge/parry/block of RQ, are simply going to eat too much game time. So something closer to the opposed check and fight back mechanics of Call of Cthulhu fits better – and the fight back can be described as the ripostes and counter-strikes of rapier play.

For dual wield weapons, borrow from 13th Age and have the secondary weapon hit on rolls of 2, but also fumble on a roll of 22 as well as 99 and 00. (so 12, 27, 92, etc are all hits if under the general skill level required). This includes shield bash. I will figure out how to handle bucklers when I build the equipment list.

Armour will be fixed values (because its faster than making AP rolls), with the best plate armour having a maximum of seven AP (so a d8 damage weapon can hope to do some damage). Armour imposes no penalties to skill use, except through the fatigue system.

Use CoC7E success levels, so an Extreme success (one fifth of base chance) inflicts increased damage, while a Critical success (01% chance) ignores armour. I am still thinking about the increased damage. Just maximum damage on one die will be plenty if its combined with the armour penetration rule below.

Gunpowder lethality will be represented by having any penetration cause a serious wound. For non-gunpowder weapons, I will do a pass for damage consistency, eg one-handed martial weapons should all do d8 damage, and not have a spread between d6 and d10. I will have to sit down for an afternoon with the weapon and armour tables I build, plus expected PC HP levels, and do a few white box combat tests. Part of session zero will be getting the players do some PvP with their character builds to see how it all works.

Exploring the Ports of Light in a d100 game

After thinking a lot about social and combat encounters, and magic systems, I decided to write a post about exploration instead. After all, its supposed to be one of the big pillars of roleplaying games. First up, I don’t think a d100 core mechanic has any inherent advantage or disadvantage when it comes to making exploration part of the game, unless it helps your GM prep by buying a lot of the cheap d100 content generation tables on drivethrurpg.com.

When I started playing roleplaying games about 40 years ago, exploration was largely focused on “-crawl” play eg dungeon crawl for specific locations, or hex crawl for exploring a geographical region, with the players making decisions about risk and reward in deciding where to move next. The game system then provided rules for:

• verisimilitude rules for representing reality in a game, such as calendars and time, movement rates, and weather.
• spot rules for hazards, such as falling damage.
• wandering damage tables (random encounters that cost resources or threaten the PCs)
• inventory management rules for characters, so that food, water, and other necessities need to be tracked and accounted for.

The problem is that inventory management is not a fun activity for players. It also requires some paperwork for the GM (per Gygax “YOU CAN NOT HAVE A MEANINGFUL CAMPAIGN IF STRICT TIME RECORDS ARE NOT KEPT” emphasis in the DMG page 37). Many modern game designs make as much of the player facing problems as possible go away. For example, in the GUMSHOE games, you can spend points of your Preparedness ability to have a useful item to hand, even if you did not write it down on your sheet earlier. Another technique is to use a die to represent resources, e.g. roll the die when firing an arrow, and on a 1 or 2 you might run out of arrows or step the die down in size. A countervailing trend, are games that deliberately lean into the inventory management, making it a critical part of gameplay, eg Torchbearer. In these games, the decision around whether to drop a torch or first aid kit, so that you can carry an extra bag of gold coins out of the dungeon is a core part of the game experience.

As for a philosophy of why exploration is fun, the best take I can find in a day of searching and reading comes from The Angry GM, exploration is the satisfaction of curiosity. Other useful articles include The Alexandrian’s take on Hex Crawls, and Ben Robbins West Marches.

So you can push the PCs out of the tavern on a quest to find the macguffin, and the players will search until they discover it, at which point this push-exploration stops. If the players are curious about the world, however, they will see something interesting and want to go and check it out. This pull-exploration is a meaningful choice, derived from player investment in the game world. The players may have different interests, and be pulled in different directions. Exploring may be a distraction, or obstacle, from the current party goal. The time and resources exploring may require is an opportunity cost, and a risk/reward trade-off. Exploration becomes a series of choices, not just an activity or nested loop of play procedure.

Detail from map of Dragon Pass. A good map will evoke interest from players. The map of Dragon Pass is one of my all time favourites.

The d100 games I am most familiar with are largely descended from the verisimilitude game engines of roleplaying antiquity, with detailed encumbrance rules. Exploration does not get the same level of thematic attention as combat and magic do, except in Call of Cthulhu. I think CoC has a central exploration theme, with players choosing to pursue the knowledge that can be found in grimoires of spells and Cthulhu Mythos lore. This is definitely something I want, a game of book hounds, seeking rumours of ancient tomes of lost knowledge, with which the world might be healed of its hurts from “All-Banes Day.” So I will build things into the game from the start for the players to discover in play.

Introspection is internal exploration – where players explore what their character is about. This is not something the older d100 games are optimised for, although in CoC you may get to discover how your character goes insane, that is not an activity the players want to have happen. The randomness of the experience system can produce some surprises about how quickly your character grows in some skills and not others. The more modern d100 designs can put an emphasis on internal emotions through the passion mechanics. As I already want to integrate passions with the setting and the experience system, I do not think I need to do much more with this. I could introduce a specific downtime activity between adventures that is “soul searching” and self-reflection on your character.

Encumbrance Rules

A short overview of how the main d100 games in my collection handle this:

• Basic Roleplaying: Encumbrance (ENC) is an optional rule. A thing you can carry in one hand is one ENC, two hands is two ENC, with tables to specify the ENC of armour, shields, and weapons. ENC is mainly used to reduce your Dodge skill.
• Runequest in Glorantha: Your max ENC is the average of STR and CON, with STR as a maximum. If players and GM agree on a reasonable carry, encumbrance can be ignored. The “things” system from BRP can also be used. Every point of ENC above your max load reduces movement, and most skill use by 5%. All ENC (even below max load), reduces Dodge skill by 1% per ENC.
• Mythras: Characters can carry STRx2 ENC. Greater loads make skill checks harder, reduce movement, and increase effort for fatigue. Armour also reduces initiative, but while worn only counts as half its normal ENC value. An optional simpler system lets you carry half STR in items, ignoring worn armour. Fatigue comes in ten levels (fresh to dead), and in the Mythras campaign I ran my players regarded “Wearied” (level 4), which reduced skill value by half as the point at which life became hell.
• Call of Cthulhu: Does not really bother with detailed encumbrance rules – but this game does not normally feature the PCs wearing heavy armour.
• Revolution D100: does not recommend tracking carried weight. Fatigue only plays a role if the GM wants it to.

Map detail of Southern Mirkwood for Adventures in Middle Earth.

Other Games

I am going to look at few non-d100 games for inspiration.

• Ultraviolet Grasslands: in UVG some of the ways that PCs can gain XP is by eating meals in the locations they are traveling through, as well as spending gold on carousing in the local den of iniquity, seeking out intense new experiences, and the wonder of new creatures or landmarks. The point crawl movement map gives the party a limited number of choices for moving onward, usually not more than three.
• Symbaroum for 5E: this setting for D&D tries to make exploring the Davokar forest a dark and scary experience, dividing the forest into bright, wild, and dark zones of increasing difficulty. The system eliminates the normal D&D classes that have features that eliminate the hazards of exploring (like Druids and Rangers). Rests take longer: a short rest is an hour, a long rest eight hours, and a full rest requires 24 hours in a safe place. There is a Death March rule for forced marches, where forced marches require the PCs to make death saves. If my players had wanted a d20 game, I would have used this as a base, along with Adventures in Middle Earth.
• Adventures in Middle Earth: Lord of the Rings for D&D 5E, now out of print. Largely an adaptation of the first edition of The One Ring. Terrain was divided into five types, from easy to daunting. Winter increased the peril rating by one. Using ponies or boats mitigated the first level of exhaustion on the journey. Journeys were divided into short (1-15 hexes), medium (16-40 hexes), and Long (41+) hexes. The longer the journey and the more difficult the terrain, the more encounters the party faced. Checks were also made at the start and end of the journey. The peril rating of the journey also increased all DCs.
• The One Ring (2E): The party needs to allocate the roles of Guide, Hunter, Look-out, and Scout between the PCs. On a journey the path is determined between origin and destination. March tests are made, on a success the party advances three hexes before an event is triggered. On a failure they move two hexes in Spring/Summer and one hex in Autumn/Winter. Entering areas of peril always triggers events. Events often result in fatigue for the PCs, a skill check for one or more PCs based on their role, and are more likely to be hazardous in wild or dark lands. Fatigue from the journey can be reduced by a mount, a travel roll, and prolonged rest in a safe place. Long journeys of 20+ hexes may require stops in safe places. This captures the mood of travel through the wilderness, and I like the emphasis on mount quality in reducing fatigue. That gives players a reason to own multiple horses, like a medieval knight did with their chargers (warhorse), palfreys (riding horse) and pack or cart horses.

Detail of the Eriador Map for The One Ring (2E). Green hexes are Border Lands, Tan hexes are Wild Lands, Orange hexes are Dark Lands, and regions with a red border are Perilous Areas. The player facing map has less information.

It seems I have a gap in my rpg collection where it comes to games or supplements that feature nautical travel or exploration, 7th Sea being the notable exception. Sailing ships do suffer from the same problem as space ships in sci-fi campaigns – any credible threat to the ship is a potential Total Party Kill. Perhaps a combination of point crawl and TOR hazard levels. The well known points are largely at ports, or other safe harbours where galleys and ships can land for water. Journeys that hug the coastline would be relatively safe, while those that cross seas and oceans would be riskier. If the journey passes by a point of peril, such as a pirate haven or sorcerer haunted isle, further perilous encounters could occur. Weather would factor in here, the old joke being that the Mediterranean has three sailing seasons: July, August, and Winter. Ship and crew quality could adjust encounters and outcomes like fatigue. Sly Flourish has a post on point crawls with links to a few other related topics.

Detail from Ultraviolet Grasslands point crawl map.

I think fatigue in TOR is a mechanic that makes interesting decisions for journeys – at what point does the party decide between pressing on, seeking shelter, or turning back? This will need a conversation in session zero about expectations, as I think the default in modern gaming is that narrative hand waving will occur, rather than it may occur. At the same time I want the paperwork element to be simple. TOR manages this in part by making Endurance, which is also HP, be what load is compared to. It also just focuses on war gear. Players can that easily spot when their PC is about to become wearied by fatigue, as Endurance is already a number they will be paying close attention to.

I do not think traditional d100 Encumbrance creates meaningful decisions at the tactical level, which accords with my own experience in medieval re-enactment. People who are used to carrying a load can move and fight with that load for well beyond the duration of even a very, very long tabletop roleplaying combat. Where it might be a factor, is when fresh combatants engage fatigued combatants – and I think that situation can be handled with advantage/disadvantage.

In the Mythras campaign I ran, fatigue only produced one memorable moment in the campaign, when one PC was separated from the rest of the party, and subject to a magical cold effect that was forcing Endurance checks. By the end of the campaign we had stopped tracking fatigue in combat.

TOR can be interesting at the tactical level, in that when Fatigue plus Load rises above Endurance, you can temporarily alleviate the problem by discarding a shield or removing your helm. If I have a “willpower” system for combat stunts, then spending willpower to ignore fatigue for an action sounds good, but the luck mechanics I am already experimenting with might do the job as well.

My design decisions

A “ports of light” point crawl design will help facilitate travel mechanics, and discovery of points of interest far away from the initial home base location will help evoke the Renaissance theme of rediscovery. This is a play on the “points of light” approach for making an adventure friendly world. Ports will generally be safe havens, with the interior of islands out of sight of the sea being more dangerous.

I will design an evocative map to spur player interest in the world. Little pictures to spark curiosity, rather than text based lore dumps, like the RQ Dragon Pass maps. There will be a player map and a GM map with some hidden locations. The geography will also tell me something about the weather.

I will build a calendar for the campaign world, and a sheet to record the passage of time, so that the time a journey takes to complete is relevant to player decisions. “Can we sail there, and get home safely before the winter storms?” I will have a conversation with my players about whether the RQG norm of one adventure per season is one they are happy with.

The equipment list will need ships and mounts of varying qualities.

I will need to think about what is known, what is unknown, and where and how the unknown might be discovered. A quick list of things that I think the players will be interested in discovering in the setting:

• Develop a number of mysteries for the players to stumble over and investigate if they wish
• Safe havens where they can rest and recover fatigue
• A way to enter a forbidden city (or other gated area)
• Places to go shopping for exotic goods
• A few places to explore in depth, worthy of repeat visits
• Locations where they can find trainers for downtime spent on improving characters
• Short cuts
• Free XP from picaresque encounters that surprise and delight
• new point locations on the edge of their known map.

I think I can adapt the TOR fatigue rules for d100. In TOR 2E, the starting Endurance range for PCs is a range from 20 to 29, although within each culture its normally a three point spread (eg 24-26). This is close to the HP range I was planning for a d100 game (20-30 HP), which means that I could use the TOR endurance, load, weariness, and fatigue mechanics. In TOR a one handed weapon is 1-2 load, a two handed weapon is 3-4 load, armour varies from load 3 for a leather shirt to load 12 for a coat of mail, plus 4 for a helm. Shields are 2-6 load depending on size. Load only measures war gear and treasure – ordinary clothes, blankets, and tools are not counted (but the number of useful items you can carry is limited by culture wealth – which would be an issue with my players who hoard possibly useful items like a squirrel storing nuts for winter).

For a renaissance setting, big heavy shields are unlikely (they fell out of use with the rise of plate armour and polearms). Pistols and aquebus are fairly cumbersome items, so they would be load 2 and load 4 respectively. A big musket (built to penetrate armour) with a supporting rest to allow it to be aimed might be load 6. I can extend the armour table, which in TOR is more dark age than medieval. Plate armour would be load 15, pistol “proof” armour would be load 18 (or 5 for a helm), and aquebus proof armour would be load 21 (or 6 for a helm). I will explore the topic of renaissance arms and armour further when I do a post on combat.

D100 – Skills

Part II of many in a series looking at my design choices in building a d100 game system. This post is looking at skills. Given how much of the text in rule books is devoted to skills and how they are used, this post is just the tip of the iceberg for this topic.

Back in 1978 the first edition of Runequest (RQ) introduced a new approach to roleplaying games. RQ did not rely on classes and levels. Rather than restricting play within archetypes like D&D, RQ allowed characters to adopt a wide range of skills, weapons, armour, and spells.

Cover art from RQ2

d100 Core Mechanic

The d100 game mechanic is seductively easy – you have a skill % to check when you attempt an action, so you roll some dice to generate a number form 1 to 100 – and if the roll is equal or less than your skill, then success! Otherwise you fail. Some d100 games specify automatic success or failure on rolls of 01-05% and 96-00% respectively.

Its a roll under mechanic, so differs from D&D where high rolls are nearly always better.

Degrees of Success

As well as success/failure, d100 games usually have degrees of success:

• A Fumble is the worst possible failure, and might occur on between 01 and 10% of rolls.
• A special success usually occurs about one-fifth of the time.
• A critical success might occur anywhere from one tenth to one twentieth of the time, or even as low as only happening on a roll of 01%.

d100 games do not usually have mechanics that “fail forward” or have success “with complications”, except those that occur from following the gameplay procedures, eg when you parry your weapon may take damage and break.

Degrees of success can be called “roll under blackjack”, as the best roll for winning an opposed check is to roll exactly your skill level, e.g. rolling 67 for a skill of 67% is great, but a 68 is a bust, a failure.

Bugs and Features of the Core Mechanic

As simple as it is, the core mechanic has some boundary issues and edge cases that crop up sooner or later in play:

• Whiffing: if you had a low skill, you could fail a lot in attempting actions. In combat this could be frustrating and life threatening to the PC. In investigations it could stall play as you tried to find the clue to get to the next lead in the mystery.
• Blocking: at high skill levels, opponents could stalemate, with successful attacks being consistently parried or dodged. This leads to a game of waiting until someone gets a critical hit.
• Rolling to suck: on character sheets with long skill lists, it is not uncommon in some d100 games to have a lot of skills listed at 00% or 05%.

Situational modifiers might also be applied to skill checks:

• In some games this is a flat bonus or penalty, eg +20%, or -15%. This has a greater impact on low skills compared to high skills.
• Using a complementary skill, invoking a passion, buff spells, or special tools might grant a bonus (one-fifth of a skill in Mythras, up to +50% in RQG)
• Applying a multiplier, or dividing the skill (eg hard difficulty in Mythras reduces skill by one-third)
• Advantage or Disadvantage on a roll, where an extra 10s die is rolled, and either the best or worst outcome kept. This has a greater impact on medium level skills, while low and high skill ranks are not so greatly influenced.
• Call of Cthulhu 7E (CoC7E) has an interesting approach. Against opponents with a skill below 50%, difficulty is not adjusted. Against opponents with skills between 50% and 90%, difficulty is hard (reduce your own skill by half), and against opponents with 90%+ skill, difficulty is extreme (reduce skill to one-fifth).

A range of dice tricks have also been experimented with over the years:

• Luck, Hero, or Fate points for rerolls or changing success levels
• Flipping the roll, e.g. a 72 becomes a 27.
• Divine intervention mechanics
• Changing special successes to doubles, rolls in ending in 5 or 10, or in RD100 having critical success occur when the singles die is less than the ten die (eg 54% is a critical success, 55% is not)
• In CoC7E, you can escalate the stakes with a pushed reroll, with failure on the second roll being worse than accepting failure on the first roll.

My recollection is that an old Wizards of the Coast survey found that a success rate of 60-70% was considered fair by players of D&D. Some of the solutions that can make d100 games feel fairer to the players have included:

• Only calling for die rolls in stressful situations, eg you ask for Drive skill checks when your car is being pursued by monsters, not for a milk run to the supermarket.
• Specifying competence levels, so judgement could be applied for when to call for a roll, eg in Basic Roleplaying (BRP) 0-05% in a skill is Novice competency, 06-25% is Neophyte, 26-50% is Amateur, 51-75% is professional, 76-90% is Expert, and 91+% is Mastery.
• With opposed rolls, specifying that whoever got the higher degree of success would succeed, or having a method to break the tie, eg attackers win ties in CoC7E.
• In Mythras and similar games, the method for calculating standard skills on the sum of two ability scores, usually results in a much higher minimum skill level than the 05%.

Cover for the player’s handbook of Call of Cthulhu 7th edition

Skills Over 100%

Skills over 100% are well into heroic or super heroic levels. While there is always a chance of automatic fumble or failure, different d100 games handle skills over 100 in different ways:

• Mythras and RQG – your skill over 100 reduces your opponents skill level, so if you have 120% skill, a foe with 80% skill has 60% effective skill.
• BRP – split the skill in two or three, so 120% could become two actions at 60%, but each action has a minimum of 50%.
• Cthulhu reduces skills by half or more, so until you get close to 200% skill it can cope.

Experience progression over 100% can be a bit tricky, usually its a d100 roll with a modifier from something like INT, trying to score over 100.

Skill Lists

So how many skills should the game have? Too few and all the PCs quickly become indistinguishable from each other. Too many, and suddenly you have a five page character sheet with entries for “Underwater Basket Weaving”. It makes sense for a gladiatorial themed campaign to have several dozen weapon skills, but that would out of place for a game where schoolkids investigate mysteries in a small town. A quick comparison of the number of skills in some different games:

• Runequest in Glorantha (RQG): 104 skills
• Mythras: 22 standard skills, plus 36 professional skills
• Call of Cthulhu: 47 skills
• Revolution D100: 15 skills (further differentiated by a large number of traits)
• Basic Roleplaying: 66 skills

Sometimes skills can be bundled in packages, eg a Combat style in Mythras might cover use of five weapons, or a range of skills might be connected by a cultural background, profession, archetype, or social organisation. Some skills require further definition, eg a Lore skill might require you to pick a specific field of expertise, so the number of skills above is an undercount. The BRP supplement Enlightened Magic is interesting in that has tiers of magic skills, known as circles, and you cannot learn the next tier until you have at least 75% skill in the previous tier. This kind of sequential skill is rare in d100 games.

Some skills might be evocative of the setting, such as Cthulhu Mythos in CoC, Sense Chaos in RQG, Torture in Aquelarre, or Seduction in Mythras (as a hyper-specialised form of Influence, Seduction is only available to few professions, suggesting that arranged marriage is a common institution in the default setting).

Something else to consider is rarity in the game world versus rarity in heroic adventurers. Its a classic design mistake to go from “this skill is rare in the setting” to “this skill must also be rare for PCs”.

The Cthulhu Mythos skill is an exception to the general rule that a higher skill is always better. Your maximum Sanity score is equal to 100 minus your Cthulhu Mythos score. Failing SAN checks can result in loss of control over your character. While this was an innovative mechanic in the 1980s, I am uncomfortable with it now, with its link to outdated stereotypes of mental illness, and its embedded reflection of H. P. Lovecraft’s racism and xenophobia. The Awareness skill in Masks of the Mythos sounds more interesting – as your knowledge of the truth of reality increases, your character is less subject to the whims of fate.

Cover Art for Mythras, note the homage to RQ.

Skills as a Universal Mechanic

I do not think d100 skills are quite as fractal as Aspects in FATE are, but the 1-100 range and die roll does get applied to things that are not quite skills. These are mostly commonly life or death skills (saves) and skills that focus on interactions with NPCs:

• Saving throws such as Dodge, Endurance, or Willpower (some of which in early d100 games were resolved via a “Resistance Table” that involved an opposed contest between ability scores). Unlike other skills, you do not want to be rolling saves – making the roll in the first place indicates a failure (this is really clear in Mothership, where your saves often have low values).
• Passions – an emotional element that can tie you to NPCs, ideologies, and social organisations
• Reputation – how you are perceived by others
• Honour – as a constraint on your own actions (less murder hobo, more social work)
• Credit rating or wealth – used in some social scenes or purchasing equipment.

One thing I found with saves, is that the players in my last d100 campaign felt that having anything less than 90% in a save made them feel incompetent in an opposed check, because they both had to roll under their skill, and above the threat roll. Which gets to the fairness thing above, I think that without luck points, the save system would not have worked for them.

How Powerful are the Player Characters?

I think there are two parts here. First, how powerful are they when created, and secondly, how quickly do they progress over time. I will have another post on experience later, so for now I will just focus on power at character generation. Going by the defaults for a few different games:

• BRP: for a normal game 250 skill points (to max 75%), for a heroic game 325 points (to a max of 90%), for an epic game 400 skill points (to a max of 101%), for a superhuman game 500 skill points (no limits). Add 80-180 points based on INT (x1.5 for heroic, x 2.0 for superheroic, and x2.5 for superhuman games).
• CoC7E: skills vary by starting profession (usually EDUx4, or EDUx2 plus another ability score x2), plus INTx2. Some profession points may need to be spent on credit rating. So a PC with EDU 55 and INT 65 might have a total of 350 skill points. I am not seeing any cap on initial skills, but maybe I missed it in the rules.
• Mythras: 100 skill points from Culture (max 15% increase in one skill), 100 skill points from Profession (max 15% increase in one skill), 150 bonus skill points (max skill increase +15), for a total of 350 skill points (on top of base skill levels that are often higher than in BRP). As its hard to increase one skill by more than 45%, starting skills are rarely above 75%.
• RQG: a history life path system can change some skills, most professions then grant +10-30% in around ten skills (around 150-170 skill points total), cults then increase a few more skills by +5-20% (total 75 skill points), and then the character gets four skills at +25% and another five at +10% (to a maximum of 100%). So a typical character has around 385 skill points.

A common option is to give more skill points to older characters, possibly at the cost of reduced ability scores. You could also shortcut a lot of point crunching by simply handing out the a number of skill levels for the players to allocate, eg one skill at 90%, two at 75%, etc. Initial power can also depend on what skills are open to the character, magic in particular may be restricted to a limited number of professions. Most professions have access to around ten skills in the games listed above. Which suggests that a group of five PCs will be able to cover most of the bases if the skills list is not too much bigger than 50.

My Design Choices

Depending on how discussions with my players go, I am leaning towards a skill model using CoC 7E as a foundation, with a few changes:

• Initial skill points: I am looking at closer to 400-430 points at start. I may allocate points equal to the ability scores, using the Mythras base scores to determine where they can be spent (after some modifying for a SOC ability score).
• Fumbles will be a player choice on rolls of 99 and 00, but generate an XP check in that skill for everyone in the party, and the GM will take suggestions for what the fumble complication is from the whole table.
• I am comfortable keeping critical success at 01%, as each PC will have some kind of dice manipulation trick. This also reduces the number of critical hits scored on the PCs.
• Advantage/Disadvantage for situational and environmental modifiers.
• I am thinking about using tiered skills for both combat and magic. More on that in posts on those topics.
• If the setting is magic rich, I may have a specific magic perception skill called Second Sight.
• To help evoke the feel of a Renaissance setting, I will have an Operate Printing Press skill, and a Liberal Arts skill that includes the seven lore fields of Astronomy, Mathematics, Geometry, Music, Rhetoric, Grammar, and Dialectic (or Logic). If we want to muck around in boats, I may add a couple of nautical skills.
• I like the idea of a skill like the Awareness skill above, but perhaps called Illumination (although that term has some specific meaning in the Glorantha setting, my players will not be familiar with it, so it will not cause any dissonance in play). This skill would be earned during play.
• Because I might have “Willpower” points for both magic spells and non-magic stunts, I may rename the Willpower skill to Abyss Gaze.
• Languages, there will be a lot of these in the setting, and no common tongue, so I will have each PC start with three languages, the first at EDU, the second at EDU/2, and the third at EDU/5. All PCs are assumed to be literate. Because part of the game will be about finding ancient lore, every five skill points spent in character creation on a language, gets you two points in a related tongue, and one point in an unrelated tongue.
• Rather than create a lot of culture and professions that the players might not use, I will either use those in one of the above rulebooks, or let the players mix and match to fit their character concept.

Building a d100 Roleplaying Game

Changed the blog theme for the first time in about a decade. I need to figure out a better widget for displaying a menu of past posts.

This post is the first of several on the topic of building a d100 roleplaying game for use in a campaign I plan to run. The design process is one where I take different bits of rules from different d100 games that I like, and stitch them together into what is hopefully a coherent design for maximum game fun at my table. This is me working through my preferences from existing games, plus my judgment about what will work for my established group of players, rather than me trying to design a new d100 game engine from scratch.

First, my reasons not to just run with a published d100 game that I already own:

• Warhammer Fantasy Roleplay 4th Edition: A bit too tied to the setting, and I am not convinced the core combat/magic rules are robust enough without buying a couple of expansion sets.
• Zweihander: Too fiddly, too pretentious, and I’m still annoyed at how much the author spammed their work on the roleplaying forums I read (before he was perma-banned).
• Basic Roleplaying System Reference Document: Too limited and bare bones in detail – it looks a lot like it was published to prevent any kind of retro-clone OSR flowering in d100 that might get too close to Chaosium IP. Not that this stopped…
• Cthulhu Eternal Open Game License: While I am not planning a jazz age horror game, there are some good ideas in here.
• Elric!: I probably ran into random armour points for the first time in this game, which I think is a good way to deal with the players wanting to stack every single bit of armour they can find (which leads to an arms race with GM adversaries to keep combat interesting).
• Flashing Blades: not a d100 game, but I would be silly not to take a look at the first game to focus on this swashbuckling era. I think I have the ubiquity engine’s One for All lying around somewhere too. 7th Sea 2E is too much of a narrative game to be useful.
• Basic Roleplaying: the big gold book is packed full of tools for building your own d100 games. Lots of different mechanics to mine here, even though its overall presentation is a little dated compared to the new toolkit systems on the block. The Blood Tide setting could be worth picking up for some piracy and nautical rules.
• Mythras: my group played this in its Runequest 6 edition, and while there is a lot to like in the game, my group never wants to play with its action point system or menu of 50+ combat special effects again. The Fioracitta setting could be worth picking up for ideas.
• Revolution 100: another system full of interesting ideas, but I find the text presentation of these ideas hard to parse in places, and ultimately the skill list is too truncated for the kind of game I want to run, and that my players want to play. Its take on extended conflicts is best in class.
• Runequest: The second edition was one of my first roleplaying games, and I will love it forever. The current Runequest in Gorantha edition is wonderful, but a bit fiddly around the edges. I really don’t fancy running its complex Strike Rank system online. I prefer its take on passions – with risk when you invoke them – to the “Mother may I?” bonus seeking of Mythras.
• Clockwork and Chivalry: while it is a renaissance setting that my players want, I am not keen on always evil witches, witch hunting, and religious violence, which look like core elements of this setting.
• Mothership: the new hotness of indie gaming with a fresh take on d100 games. If I wanted to run a short 8-12 session campaign, I would be using this as the base game engine, even though the original game is focused on space horror.
• Call of Cthulhu 7th Edition: The latest evolution of d100 from Chaosium – in some ways showing what could have been with the latest edition of Runequest if they had not tacked backwards towards the 2nd edition for reverse compatibility. Pulp Cthulhu also has useful ideas to borrow for a swashbuckling game.

Cover of the “Big Gold Book” from Chaosium

I also plan to borrow a few mechanics from non-d100 games, which I will discuss in the relevant sections. Rather than try and cover everything in one epic blog post, it makes sense to break it down into shorter posts. In the rest of this post I will write about character ability scores (aka attributes or characteristics – I use ability because it is a shorter word), and in the next post I will discuss skills.

The Eight Ability Scores

Where D&D uses the six ability scores of Strength (STR), Constitution (CON), Dexterity (DEX), Intelligence (INT), Wisdom (WIS), and Charisma (CHA), the d100 family of games usually has eight ability scores of STR, CON, DEX, Size (SIZ), INT, Power (POW), Education (EDU), and either CHA or Appearance (APP). POW is not a replacement for WIS, and represents aptitude for magic, psychic, or other super powers, plus Sanity (SAN) in Call of Cthulhu.

Ability Score Scale

Most d100 games follow D&D and have a 3-18 scale for most of the ability scores for human characters. The exceptions being INT and SIZ with a 8-18 range. Call of Cthulhu 7E adjusts these scores into a d100 scale by multiplying them by five.

In most cases higher scores are always better, the exception being SIZ, where being small could boost stealth, allow you to squeeze through a narrow gap, or hide inside a small space.

Random or Point Buy

The traditional random rolls for ability scores are 2d6+6 for INT and SIZ, and 3d6 for the other six ability scores. So “mean norm the average ranger” will have 13s for INT and SIZ, and 10s or 11s for the other six ability scores. Elric! (1993) is a more high power system, all eight ability scores are rolled 2d6+6. Non-human PCs can have different scores, eg in Runequest 2, a Great Troll would roll 4d6+12 for STR, but only 2d6+2 for INT.

Some d100 games allowed you to shift up to three points around between your scores. In my Tarantium campaign I allowed a player to discard one die and reroll it, a maximum of three times when generating all eight ability scores.

Mythras has a point buy system. The default is 80 points, which gets you average scores of 10 in your eight ability scores, but allows you to min/max as you see fit within the constraint that INT and SIZ require minimum scores of 8. In my Tarantium campaign I increased the point buy to 84 points.

Philosophically, random rolls mean you get to discover the character you will play, while point buy lets you choose the character you want to play. For long campaigns my preference leans towards point buy. In Tarantium I let my players choose. One rolled, the other four went with point buy. For point buy systems, it is important for the GM to point out break points for derived characteristics, to avoid system mastery traps in character generation (eg, building a Mythras character with only two action points).

For a high power campaign, I might use a variation on Rafu’s matrix method, which mixes elements of choice and randomness. This has a three step process:

1. Assign the numbers 1-8, each to one of the eight ability scores.
2. Roll a pool of 8d8. From the pool, assign one die roll to each of the eight ability scores.
3. Roll 1d8, in strict order, for each ability score.

This changes the base ability range from 3-18 to 3-24, average of 13-14 (not too far off Elric!), but I am okay with PCs being special snowflakes. The original mechanic used d6s as it only had to generate six ability scores.

Progression

Ability scores in d100 games are sticky and hard to change, often requiring significant time and money to train up. SIZ is usually the hardest to change, POW the easiest as using magic successfully might allow a check to increase it. A character maximum is usually three points above the highest possible rolled ability score, so for a 3d6 score, that is 21. In some d100 games injuries can permanently reduce an ability score.

In Tarantium I sometimes awarded increases by GM fiat, to represent training that the party got from their employers.

Derived characteristics

This is one of the areas where the different d100 game engines have significant points of difference.

• Hit Points: these are “meat points” not “plot armour”, and are usually calculated on CON and SIZ, divided by 2. In Call of Cthulhu 7E, its divided by 10 or by 5 in Pulp Cthulhu. D100 games can have a mix of general HP and location specific HP. Mythras only has location HP. Average general HP is around 12, or 24 in Pulp Cthulhu.
• Action Points: a Mythras score, based on INT and DEX.
• Damage Modifier: a bonus to melee damage, based on SIZ and STR, usually represented by rolling a an extra die that is not the same as your weapon die (which I find a little clunky).
• Spirit Combat Damage: a bonus to damage when fighting spirits. Based on POW and CHA.
• Movement Rate: a critical score in Call of Cthulhu, where flight is often a better choice than fight.
• Experience Modifier: In Mythras your CHA score can adjust the number of XP you get each game session. In Runequest the skills category modifier also adjusts experience checks.
• Healing Rate: In Mythras and Runequest your CON score determines how quickly you recover lost HP, typically 1-3 HP per day.
• Luck Points: A player resource to nudge die rolls in their favour. In Call of Cthulhu 7E these are generated randomly. In Mythras it depends on your POW score.
• Magic Points: Fuel for spells, usually determined by POW. Magic Point recovery depends on how magic rich your campaign world is. In magic rich Runequest you regain 25% of MP every six hours. In magic-poor Tarantium, you regenerated 1 MP per day in a flying city, and 0 per day on the ground.
• Strike Rank: Combat initiative. In Mythras its derived from DEX and INT, with a penalty for encumbering armour. In Runequest its based on DEX and SIZ, plus a modifier based on the weapon you are using.
• Sanity: In Call of Cthulhu, your resilience in the face of cosmic horror. Based on POW x5. In my Tarantium campaign I used Areté (moral excellence) to represent moral corruption in a manner similar to SAN. I am not fond of the actual forms of madness that older editions of Call of Cthulhu inflicted on investigators, which were derived from older stereotypes of mental illness.
• Encumbrance Points: no one likes encumbrance and fatigue mechanics, but in Runequest it is based on STR+SIZ, in Mythras its STR x2.
• Skills category modifier: In Runequest modifiers to skills are based on a range of ability scores, eg Agility is derived from STR, SIZ, DEX, and POW, while Knowledge is derived from INT and POW. Usually a flat modifier of -5% to +15% to the base skill scores. Not needed in Mythras where base skill scores are determined by combining two ability scores or doubling one ability score (so a range of 6% to 36%).

Implications for Other Mechanics

High STR, CON, DEX, and SIZ scores make you good at combat. High INT and EDU scores make you a better skill monkey. High POW is needed to be good at magic. As is typical for older game engines, only APP/CHA play a major part in the social pillar of play.

Mythras makes you really consider your ability scores. There are no dump stats.

My Design Choices

First, I will use CHA rather than APP, as a personal preference.

Second, I will drop SIZ and replace it with Social Standing (SOC) and a heritage based Build score. By heritage I mean “race” in old game design language, and I want it to represent a nature/nurture/culture background choice for characters. Replacing SIZ with SOC will let me diversify base abilities for a number of skills away from CHA, INT, and EDU (which is a solid clue to how my pans for skills are shaping up).

Third, I will go with the d100 scale ability scores of Call of Cthulhu, rather than the 3d6 range. This will let me use the same experience based improvement system for improving both skills and ability scores. As to whether or not I go with point buy, or that 3d8 OSR mechanic, I will talk with my players first. 3d8 x4 will give a number broadly comparable to 3d6 x5 (with a median of 54 versus 52.5, and a range of 12-92 versus 15-90).

Fourth, Hit Points will be based on CON/5, STR/10, and DEX/10, which will give a level of HP equal to Pulp Cthulhu. I am leaning towards general HP only, no location HP, with a serious wound mechanic at 0 HP or loss of half HP in a single blow, or something like the stepped wound system in Mothership.

Fifth, Melee Damage Bonus will be based off STR and heritage build (75 for a human, non-human heritages may vary from 25 to 110). Options for implementation include the classic bonus die, a flat modifier, or stepping up the weapon damage die (ie d6 steps up to d8, then to d10).

Sixth, Movement Rate will be based off DEX and heritage build (as above). I mostly run theater of mind games, but if its needed for chase scenes its good to have it.

Other mechanical decisions will need to wait until I refine the campaign setting and expectations of play with my players. For example, I might make Luck Points only available to players who roll their ability scores randomly, while players who choose point buy get a different fate/destiny/free will mechanic to use.