Authoring Games with Tile Rewrite Rule Behavior Trees

Game authoring can be a difficult, technical process; exploring new ways to describe games and game mechanics may help make game authoring more accessible. In this work, we present Tile Rewrite Rule Behavior Trees (TRRBTs): a concept for a domain-specific language for authoring tile-based, turn-based games. The approach combines tile rewrite rules and behavior trees. Using TRRBTs, a game's state is represented as a grid of tiles, the behavior trees describe the overall flow of the game, and the rewrite rules at leaf nodes describe changes in game state. We include transform nodes, which apply transformations to other nodes in the behavior tree, allowing more complex mechanics to be expressed in a compact way. We demonstrate a text-based approach to using TRRBTs to create several simple games, show how the approach allows reuse of trees to build on existing games, and show how they can provide a unified representation for procedural content generation and enemy AI along with game mechanics.