Game Design
In board games, the board pieces are not secret, but hidden or private cards is a big part of card games. Computer games bring something new: a state or attribute only the computer knows about. The player who is aware of his hand, the virtual opponent algorithm which is aware of its hand, and the main algorithm for the game which is aware of everything about the game.
The Hierarchy of Knowers Venn Diagram helps visualize this information.
- Biggest Circle: God. Point E lies here.
- Circle Within: Game. Point D lies here.
- Three Linked Circles Within: Players 1, 2, and 3
- A - The shared space of all three circles
- B - The shared space of two circles
- C - The space kept only by one circle
Each circle represents a knower: God, Game, and Players 1, 2, and 3.
- A is information that is completely public, such as the position of a playing piece on a game board or a face-up card. All players are aware of it.
- B is the state that is shared between two players but kept secret from another. Perhaps they both got the exclusive opportunity to look at a face-down card, or perhaps they share information and team up against the other player.
- C is information private to a single player. Perhaps the cards he was dealt.
- D is information the game knows about, but not the players themselves. Some board games have structural secrets: Stay Alive had plastic sliders that when moved revealed holes in the board, and Touché has magnets of unknown polarity placed under each square of the board. A DM or GM in tabletop RPGs are not a player but privately know a great deal of the game state, since he is the operational mechanism of the game. Most computer games have a great deal of internal state that is not known to players.
- E is randomly generated information, known only by God, Fate, etc.
(The Art of Game Design: A Book of Lenses by Jesse Schell, Carnegie Mellon University, 2008. Page 137-139)