Real Time Strategy and Game Theory
When thinking of strategy games one often drifts to board games like Chess and Go, who’s play has been refined over the centuries to a near art form. Game theory can even be applied to these games given that each player knows the rules before hand and the goal of the other player, and thus strategies can be devised that attempt to take advantage of what the other player might do. However these games happen in turns and as such a players strategy evolves over time as the observe the opposing players moves, but the ideas of game theory still apply and making a best response to your opponent is still a good idea. But today I would like to talk about a different kind of game that is real time strategy games, primarily Starcraft.
I recently read an article comparing Starcraft to both Chess and Go and with the recent discussion of game theory in class I thought it would be interesting to discuss some of the differences between the standard games we have looked at in class and actual games that people play. But first lets look at some of the similarities. As in standard games, both players in Starcraft understand all the rules of the game and have the common goal of either completely destroying their opponent or causing enough damage to force a surrender. If you think about it in terms of payoffs each player receives a positive payoff for winning and a negative one for losing (oddly enough in the new version of Starcraft, Starcraft 2, there can even be draws but this is very rare so we will ignore them). But unlike most games we’ve discussed in class in Starcraft their are many “strategies” for each player. The reason I use the term strategies loosely is because it is hard to correspond them directly to the strategies we’ve discussed in class. The primary reason for this is because Starcraft is a real time strategy game. This means that there are no turns and each players decisions are not made at them same time. In fact for the entire length of the game (which can last from 7 to 60 minutes or more) players are making many decisions each second, and so the term strategy should be applied at a higher level similar to in chess where you wouldn’t say moving your first pawn is a strategy but trying to perform a specific set of moves or get into a particular position would be a strategy. This rapid fire decision making can cause the game state to change rapidly changing the payoffs for each player as the game progresses.
This leads to another major difference between Starcraft and the games we’ve analyzed in class. In Starcraft you do not know exactly what your opponent is doing at all times. This causes strategies to change not only as time goes on but as you understand more of what your opponents strategy is. For example, if you see that your opponent is building a particular unit the short term payoff to build a unit that does extremely well against his unit goes up, while building a different unit that would easily lose to his becomes a poor choice. Because, strategies can be changed so drastically based on your opponents strategy early in the game it is often beneficial to determine what your opponents strategy and at times this information can be worth much more than a few extra units.
Despite all these differences game theory can still be applied at a higher level to Starcraft. Players devise elaborate opening strategy to take advantage of what they believe the other player will do without any prior knowledge. These types of decisions are what some people refer to as meta-game. That is a decision made based on information outside the game, for example if there was recently a patch to this unit that allows it to perform better then you may want to build units that are good against it blindly. So in general, a real time strategy game is much more complicated than the simple games we discussed in class, but the principles of best responses and picking optimal payoffs still apply it just takes more work to create the payoff matrix.
If you want to learn more about these types of games I found a blog post for this course from a couple of years ago that might give you more information on the subject.