Getting Lucky in d100 Games

This post on building a d100 campaign game for a fantasy renaissance setting is about luck mechanics. By “luck” I mean a resource that players can use to adjust die rolls made in the game when the normal process has not resulted in what the player wants. As roleplaying games are in part about how you overcome obstacles to get to your desired outcomes, luck mechanics can be another way of reinforcing what the setting and the player characters (PCs) are about.

This is one of the options I got for “Free Will” on the Craiyon Art A.I.

A short overview of luck rules in the four main d100 games I usually seek inspiration from:

  • Basic Roleplaying (BRP): PCs have a Luck score equal to POWx5%. Luck is the knack of being in the right place at the right time, or the uncanny ability to escape a random peril unscathed. It can also be used like the Preparedness ability in GUMSHOE, to check if you remembered to pack something for the adventure. A POWx1% roll might be used if a PC is acting without skill, or to avoid a coup de grace attack. Opposed luck rolls can be used in some gambling games. A luck roll might be made to mitigate or avoid the potential harm from a fumble roll, to attempt divine intervention, to impart vital information while dying, or to enhance the effect of some spells. Because luck is treated as a characteristic, it is not reduced when called on.
  • Call of Cthulhu 7E (CoC7E): A PC starts with 3d6x5 Luck Points. Luck rolls can be called by the Keeper when circumstances external to the investigator are in question, or to determine the fickle hand of fate. A group luck check can be called by the Keeper, and the PC with the lowest luck score rolls to see if the entire party is affected. Alternately, the keeper can just target the PC with the lowest Luck. Optional rules allow Luck to be spent to alter the roll on a 1 for 1 basis. Luck rolls cannot be pushed (a mechanic that allows a reroll, which ups the ante with dire consequences if failed a second time). Luck points cannot be spent on Luck rolls, damage rolls, Sanity rolls, Sanity loss rolls, or a pushed roll. Criticals, fumbles, and firearms malfunctions cannot be changed by luck. No skill improvement check is gained if luck is used. Luck itself can be improved in the same way as skill improvement, but cannot increase above 99. The Pulp Cthulhu supplement has additional optional rules for luck. Of note here are that you can spend all your remaining Luck, minimum of 30 points, to avoid certain death., and you gain also spend 20 Luck to immediately gain 1d6 Hit Points. Pulp Cthulhu also increases Luck point improvement, from 1d10 in CoC7E to 2d10+10 on a successful improvement check, and 1d10+5 on an unsuccessful improvement check.
  • Mythras: In Mythras luck points represent the ability to turn failure into success, and even cheat death. Most PCs will have one to three Luck Points, based on their POW score. Luck points refresh at the start of a session. Luck points can be used to re-roll any die roll they made, or swap the numbers rolled. This can be any kind of roll, including damage rolls. Players can also force opponents to re-roll. A luck point can also be exchanged for an action point, or to mitigate a Major Wound, turning it into a Serious Wound. The party as a whole may also have a pool of Luck points, equal to two plus one per PC. So a group of five PCs will have a Group Luck Pool of seven. Group luck points can only be spent on actions that aid other PCs, and to gain information for investigations. Only one luck point can be spent on a particular action, so if you fumble twice in a row you are stuck with the fumble.
  • Runequest in Glorantha (RQG): There are no luck points in this game … but you do have divine intervention (DI). This can replicate divine feats from myths, teleport a worshiper and up to nine friends to a temple, resurrect dead adventurers, and to increase characteristic scores. You cannot ask for divine help against people who worship your God. The DI process first requires the PC to permanently sacrifice one Rune Point, then roll a d100 (initiates and priests) or d10 (for rune lords) depending on your cult status. Rune Lords can even ask after they have died (but many Death Gods will not return their worshipers to life). If the roll is over your total Rune Points + POW, your God does not intervene. Otherwise you lose POW equal to the roll (for initiates), or POW and Rune Points (for priests and rune lords), with Rune Points spent first. If a successful DI reduces you to zero POW, congratulations, your God takes your PC straight to their eternal reward.

Past Experience

Luck Points worked fine in the Tarantium campaign I ran, and largely kept the PCs alive, apart from that one incident with a Cockatrice and a petrification attack. Fumble rolls tended to result in Luck Points being immediately spent on a reroll or dice flip. We did have one player roll two consecutive 99-00 fumble rolls on a d100. DI was fairly rare in the Runequest campaigns I played in when I was younger – we had really only reached the Rune Priest and Rune Lord stage of the game when the campaign ended. I have not played CoC7E, but the BRP luck mechanic looks similar to what we had in the CoC games I was playing in 30 years ago, if I am remembering things correctly.

My Design Choices

In the campaign setting I intend to offer four heritage choices to the players. Each heritage will be associated with one form of “luck”, but not exclusively. As a setting background element, all the Gods have died within living memory, so divine intervention is not a possibility.

  • Adroit: Your heritage is still influenced by ancient magic and prophecy. You can call on Fate after a die roll is made. The action you are attempting is an automatic critical success, or you can cause a foe’s action to fumble. Hand your fate token to the GM. The GM can invoke fate in a later scene, causing one of your actions to fumble, or for a foe to gain a critical success against you. The GM then hands your fate token back to you.
  • Human: The recently freed humans believe strongly in liberty and Free Will. This allows you to use the CoC7E pushed roll mechanic.
  • Moglin: The cat-folk have always had a reputation for luck. Use the CoC7E Luck Point system. Moglins can buy off certain death nine times in the campaign. Non-Moglin who have the Luck mechanic can only buy off certain death once.
  • Taurian: Your heritage is still influenced by the call to adventure and the path of the hero. You can call on Destiny before a die roll is made. In all other respects, this works like the Fate mechanic above.

Anyone who chooses to roll their character ability scores can also choose the Luck Point mechanic. Anyone who chooses point buy for their character ability scores can also choose one of the Fate, Free Will, or Destiny mechanics. This should leave things relatively open, but still retain the colour of the setting. Significant NPCs will have access to these mechanics as well, but not ordinary people or mooks. Once again, because my players have asked for high XP campaign, I may grant a point of free XP to PCs who use their luck mechanic at least once during the game session.

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