Design ye more varied games!

What is a role-playing game? (yet another attempt)

A role-playing game is a game format. (Other game formats include board games, video games, word games, etc.) I take the definition of a game as the act of structured play within a controlled enviroment (the game space) that registers at least one variable which is accepted as 'truth' within the enviroment. The game state is the sum of variables and their information. This game state is altered by the player's actions during play.

- A role-playing game is a game where the space and action are primarily imagined and thus imagination is the primary medium. I define primary here as the medium that is sufficient for play, and the medium in this case defines the format.

- In the case of multiplayer games, some form of communication is necessary to ensure correspondence between the individual's imagined game states and changes due to the player's actions.

- All games need a codified and agreed-upon set of rules which structure gameplay, define player roles and authority, and dictate permitted and prohibited actions within the game space. 

What can role-playing games be? (more like, what elements can we play with as designers?)

- The game space can be created, controlled, and modified by one or more players.

- Players can control individual or collective entities within the game space, or even treat the game space as an entity of its own.

- The rules text can be modified, as it is not the ultimate authority during the act of play.

- The manner of communication need not be verbal but must be intelligible.

What games can exist, then? (off the top of my head)

- Controlling individual agents in a world created by one unique player named the Dungeon Master.

- Creating the history of a world in a non-linear fashion.

- Games which allow the modification of their own rules text.

- Writing narratives collaboratively or competitively.

- Jointly embodying a single character, or individually controlling collectives.

- Simulating pre-planned scenarios.

- Games with multiple assymetric roles.

- Games where the rules text is known (or not) within the game space.

- etc.

There is a wide design space yet to be explored!