The Curation Tree: A Lightweight Behavior Tree Framework for Implementing Puzzle and Narrative Games

In this work, we describe the Curation Tree framework that has matured as part of our game-based research and teaching. We use this framework to manage the top-level experience of our players via a text-based, authorable behavior tree system that is easy to implement, test, and re-use. We present three case studies based on Unity games built within our framework: the first involves virtual reality games involving grasping objects with the hands; the second, Treatment X, uses the framework to implement a causal learning game; and the last involves narrative games based on a large language model. Based on our experiences with this system, we reflect on its limitations and make several recommendations based on its strengths, namely to centralize game logic with behaviors, to centralize user event handling, to prefer simple behaviors over complex ones, to use text-based scripts for authoring with version control, and to separate behaviors from persistent state.