worldlines

WorldLines is a multi-agent simulation engine for role-play and interactive narrative, developed by Ludic Dynamics, a team of researchers from the University of Tokyo and game industry practitioners. Unlike conventional AI chatbots, WorldLines simulates a real-time society of independent AI agents: a world-agent owns the canonical world state and orchestrates a cast of soul-agents, where each character has its own persona, long- and short-term memory, secrets, goals, and inner voice. Players join through an avatar terminal and interact with agents that perceive, decide, and act autonomously. The engine is file-backed and event-sourced: every turn is an append-only event, with snapshots enabling fast rewind. All memory and world state persist on disk as plain JSON and Markdown, making sessions git-diffable and reproducible. It supports branch, undo, and redo for narrative forks, auto-indexed context injection, and sandbox replay for determinism verification. It is model-agnostic, supporting GLM, OpenAI, LM Studio, Ollama, DeepSeek, OpenRouter, and local models. WorldLines offers three engine modes. The flagship multi-agent mode runs a society of independent soul-agents in one world. The lighter orch mode has a world-agent voicing data-driven NPCs with domain agents (town, dungeon, combat, story). The fast mode is a single-voice agent for tighter scenes. Example worlds include Kagura Island (7 souls, Japanese-folk mystery with time loops), Stoneford (a TRPG-style fantasy port), Stoneford·Elena (2 souls with persistent memory), Sakura Hallway (school love story), and Lamp of Souls (a Chinese-style otome court romance). The project targets several audiences: AI role-play players seeking characters with real persistent memory; galgame, otome, and visual novel fans wanting responsive, non-branching narratives; TRPG game masters who set constraints and let agents run the world; researchers studying personality models, world models, or multi-agent societies who need a reproducible sandbox with scriptable JSON and trace output; and developers using Claude Code or custom agent pipelines. WorldLines exposes its agents as MCP tools that Claude Code discovers automatically. The repository includes authoring tutorials for creating character cards, world cards, full game worlds, and multi-agent souls. The framework is formalized in a CHI PLAY Companion '26 paper as a Parameterized-Action POMDP with a Plan-Diff-Validate-Apply pipeline. Licensing is split: example worlds, tools, web UI, and desktop shells are AGPL-3.0 open source, while the NeonRP engine core remains proprietary.