Street Fighter taught me about yomi: knowing the mind of the opponent. You can’t just play the odds and do the textbook-correct responses, you have to adapt and anticipate your opponent’s moves. The game is merely a medium through which you play against the other player.

Games vary in how much they require skill at yomi, and it occurred to me that a game including yomi skill precludes a game having a Nash equilibrium.

a solution concept of a game involving two or more players, in which each player is assumed to know the equilibrium strategies of the other players, and no player has anything to gain by changing only his or her own strategy unilaterally. If each player has chosen a strategy and no player can benefit by changing his or her strategy while the other players keep theirs unchanged, then the current set of strategy choices and the corresponding payoffs constitute a Nash equilibrium.

Stated simply, Amy and Bill are in Nash equilibrium if Amy is making the best decision she can, taking into account Bill’s decision, and Bill is making the best decision he can, taking into account Amy’s decision. Likewise, a group of players is in Nash equilibrium if each one is making the best decision that he or she can, taking into account the decisions of the others.

Wikipedia

Games like Street Fighter, Kongai, coker, chess, are interesting because they don’t have evolutionarily stable strategies, every player is obliged to change their strategy in response to another player’s change. If a game (or one decision in a game) has a Nash equilibrium, there is no value to yomi, the player doesn’t need to know what the other player plans.

• 1. Ikariam
• 2. WeeWar
• Tangent: The Farming Genre
• 3. Tactics Ogre
• 4. Counter-Strike
• 5. X-Com
• 6. Kongai
• Tangent: Technology Trees
• 7. Warstorm

Kongai is a very different from all the previous games. It’s an online two-player collectible card game. You build a deck of three to five characters (with, optionally, one item each) and defeat your opponents’ characters.

Each turn you have two choices to make and the results are resolved simultaneously rather than in the more common “I go, then you go” fashion. Range is first: you can leave your character where they are or spend energy trying to get to the near or far range. If you leave your character, the range is whatever your opponent sets. If you both try to set it to something different it doesn’t change. Some abilities work only at near or far, some both. The energy you spend to change range is the same energy used to activate abilities, so there are immediately some tough decisions to make about where and whether to spend your resources and guessing what your opponent will choose.

Second, you each choose an action. You can use one of your characters’ four abilities (mostly attacks, though a quarter or so heal or give status ailments), switch your character out for another (dodging any attack), intercept your opponents’ switch (preventing it and dealing significant damage), or rest your character to recover extra energy for the next turn.

It’s one of those simple-but-deep games because of the simultaneous turns. You don’t flail away at your opponent, you have to outthink them. Kongai’s designer, David Sirlin, has written a bit about the process of designing Kongai and how it’s all about the skill he calls yomi, the ability to predict your opponent’s moves and keep yours unpredictable.

This, in a nutshell, is why I gripe about multiplayer games being primarily about deckbuilding like Tactics Ogre. You only get one try to guess your opponent’s plan. If you guessed wrong, you play a (possibly quite long) battle that you can probably only lose. Only then do you get a chance to change your build to have new tactics to try again. Tactics Ogre isn’t much fun because there’s little back-and-forth between the players, battles are just about lining up and smashing as hard as you can (or, worse, about “leveling up” the power of your characters).

Deckbuilding isn’t intrinsically wrong, it’s fun in Kongai and in Magic: The Gathering even more of the game is deckbuilding and it still works well. Many strategy games like Civilization and StarCraft intertwine the building and using phases. You scout your opponent and deceive their scouts to decide your build and sabotage theirs.

Sirlin’s written an awesome book called Playing to Win: Becoming the Champion about how players should approach competitive games to succeed at tournament-level play (it’s also available free online). His pushes players to understand games as they are designed rather than as they may stylistically appear to play. Basketball can be won by playing the court and constantly harassing other players, not by executing a practiced attack or defending the zone (the Traveller example is even more powerful). I also recommend reading Sirlin’s entire blog, it’s similar in content to his book but from the perspective of the game designer trying to plan and balance a complex game that elite players will do their best to break over thousands of hours of dedicated play.

I was thinking about my game’s design and how to prevent it from becoming a slugfest when I thought of Kongai and read Sirlin. The best strategy in any farming game like Ikariam is to find the weakest player and raid them repeatedly. The best strategy in WeeWar is to steal an opponents’ nearest base and the positive feedback loop generated by bases being a zero-sum resource means you’re almost guaranteed a win. Tactics Ogre is a slugfest because there are no meaningful options, the best move on any turn is to move to the weakest opponent and hit them as hard as possible. The constant refrain here is that you never care what your opponent is doing; nothing they do actually influences your moves because you don’t have significant decisions to make.

Counter-Strike is a highly successful tournament game because players are constantly shifting tactics in the real-time battle. X-Com is the only single-player game on this list, but it would have a good shot at translating to multiplayer because it deals with managing limited resources and knowledge in response to your opponents’ actions.

These are the games that had the biggest influence on my design, though there are certainly others like Syndicate, Eve Online, and muds that have had an effect. I seem to have a habit of working on my design, seeing flaws, adopting from other games to refactor my design, and repeating. I’ve been really happy with my current plans for an unprecedented several months, so I’m moving into playtesting to start getting real-world feedback on how well gameplay works. I’ve got one more game design blog post scheduled on technology trees and otherwise will be returning to my regular babbling about whatever shiny thing captures my attention — which is to reiterate that you should feel free to comment, email, or IM because that’s where I tend to pick up topics from.