Core Components of Game Theory in Video Game Design
For purposes of game design, we can simplify the application of game theory to four components: Players, Actions, Payoff, and Information. These core components are then the basis for the full rule set of a game.
First we must define the players. For this discussion, we will assume that players are competing against each other and not playing a cooperative game. As a player they will assume that they are playing by the same rules as everyone else playing the game. That is, they have the same goals and strategies available to them (or at least a balance of resources and goal objectives). Game theory shows us that strategies change as more players are allowed to participate. For example, a one-on-one strategy card game becomes a very different experience when a third player joins.
Actions define what the players can do and when they can do them. Many times players react to other objects acting against them ( obstacles and enemies ). The actions players can take and the conditions under which they can take them usually define the rules of the game. For instance in paper, rock, scissors players can only use one hand to symbolize one of three choices – paper, rock or scissors. The players can only show their hands at the same time and the winner is decided by which choice is dominant based on pre-determined and known information.
Games usually structure a decision point where players will make choices that affect their immediate standing in the game. A common decision point in video games is a turn. That is, players each take a turn to declare decisions and take actions like in chess or checkers. Decision points can also be free form or simultaneous, which again, sets up a whole new set of strategy paths and outcomes.
Payoff / Goals
Payoff is next thing players notice in your game after learning about the initial player character and the actions they can take. The payoff for playing a video game is subjective, but generally involves a sense of self accomplishment or entertainment by beating an opponent or achieving a feat of some kind that takes skill and technique. Remember, players are likely to experience some defeat and frustration so there must be some intrinsic value to playing the game itself. The game must be fun or entertaining even if the player loses. As game designers we manipulate this concept of payoff constantly in an attempt to achieve flow and fun. In other applications of game theory, payoff can be a much more serious component, as say in the Prisoner’s Dilemma scenario or in creating economic policy.
Our last component is Information. What does each player know as they start and play through the game? What do they not know at each stage of the game? Remember in the Prisoner’s Dilemma the information the accused had was crucial to how they approached the problem. They both knew all the choices available to the other, but they did not know the decision on those choices the other would make. Changing any information, however, has a huge effect on the game. If the prisoners have faced a similar plea deal and know the previous outcome for testifying was less than optimal, that knowledge might play an important role in their decision the next time the scenario is presented.
Together, these essential components and the variations they can form help designers balance their game. These components combine to create a stable platform for games that can be functional and predictable. Yes, as game designers we do want some predictability. We don’t want the game to be an exercise in predictability to the point of pointlessness, but we do need a certain amount of it in the rules so the game has stable structure. Players expect a level of consistency as they replay games over and over.