Building a better tech tree

I have had a stimulating couple of weeks working on some ideas for Colossus of Atlantis II. One goal for the redesign is to have a better tech tree. Last time the research game was “go fish” in the card deck, followed by “collect a set” trading, and for some of the teams, eventually building a colossi or two. I think I can do better next time. Ideally I want every team to have the chance to put Colossi on the table in time for them to make a difference. I am also keen to move away from people holding large piles of cards for trading – I want trade negotiations to focus on a contract like piece of paper where people haggle over the split of profits.

Tech trees have always been a staple of RTS games, but they go back further, to the old Civilization boardgame (1980), if not earlier.

Some of the design questions you need to consider in building a tech tree include:

  1. Is the research order set? How much choice do you want to give the players – this can be crucial if there is a system mastery challenge where some options are better than others.
  2. Is the research order known to the players? If its known it can be a spoiler, if it is not known the uncertainty will change player strategies.
  3. Can steps on the tech tree be skipped? If players do screw up, is there a catch up mechanic?
  4. How much control do the players have over the research effort?

Technology developments can be great rewards and motivators. Its a way of adding complexity to the game as the players master the core rules of the game, by adding new capabilities to the game mix.

Time is a constraint in megagames. You will only be able to process a finite number of game turns. If you make the tech tree too big, teams will never complete the end of the tree, and this may disappoint the players. This suggests you need to calculate the resource fountain or flow dedicated to research, against the cost of the options. You definitely want a playtest of the system. After several turns what does it look like for teams that focused on research, ignored research, or did a bit of research?

Because technology can be used to change the game rules, you also need to consider how this change is reflected in game state information. All the other players and GMs need to be able to verify and understand the research outcomes. Keeping things simple is always a good idea.

In real life, tech change tends to be evolutionary, not revolutionary. One thing I would not want to do, is to have one option in the tech tree that is a dominant strategy. Some teams will spot it, others may well miss it until it is too late.

Putting this all together in a new package

I usually have about four hours available for a megagame, and get through about eight 20 minute turns, after briefings and delays are taken care of. So I want less tiers of research than I expect game turns. I think the tech tree should be open knowledge to the players, especially as I want to run the game more than once.

Because each team should have five players, that sets the upper bound of research effort each turn – five attempts to generate research points and buy technology cards. That means no more than five branches on the research tree. With the mechanics I have in mind, at the start of the game a player should be generating 1-12 research points a turn. By the end of the game, a player should be generating 2-24 research points a turn.


This is a table I put together quickly, so the numbers might be fine tuned later. It has four tiers of research, although I might extend it to a fifth tier as well. There are two concepts represented in the cost/reward structure – diffusion of knowledge and diminishing returns.

The first team to research a breakthrough pays the highest cost, but reaps the greatest reward in Victory Points. The costs diminish as the knowledge is spread throughout society, but the Victory Points drop more quickly to zero. This can be done by building a card deck, set in a prearranged order, so the cost of the top card is the highest cost, and so on down to the cheapest and last card.

If a team focuses on maximising research, they should unlock most of the tech tree within five turns, granting them three or more turns to enjoy the fruits of their labours. A team focusing its efforts elsewhere, can catch up with a bit of effort.

I do have some problems to work on. First, I need a way to make it clear who gets the privilege of choosing cards first (it could just be random).

Second, because I need to keep the research card decks in one place, but my initial map design has multiple maps where research can be generated, I need to find a way to accurately transmit information about research (do I give the players cards or token chips, or rely on Map GMs to coordinate the information).

I also have not decided exactly what the research will do, but it is likely to be a mixture of:

  1. Adding more units to a team’s force pool.
  2. Improving the capabilities of controlled units (e.g. rolling a d8 rather than a d6).
  3. Changing game rules.
  4. Unlocking new types of units, such as the Colossi.
  5. Allowing the build of ancient wonders of the world.

One option I am considering, is allowing a narrow thrust up the tree to unlock the Colossi at Tier IV or V. But all the branches of the tech tree lead to Colossi (each gives the Colossi a different capability). After all, making a game about giant steam bronze robots, and not letting the players use and enjoy such leviathans, would not be good design.



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