What is Gnosis Engine?

Gnosis Engine is a Unity runtime package that gives you:

• A single shared state tree split into Persistent (settings, unlocks, configuration) and Ephemeral (per-run roguelike state).
• Services with stable string ids (e.g. Money, Shop, UserInterface) that own slices of that state and expose named functions (InvokeFunction).
• An event bus plus data-driven rules (JSON under Persistent.configuration.rules) that can intercept events, observe facts, or trigger side effects.
• Unity adapters (UnityGnosisAdapter subclasses) that bind engine services to UI Toolkit, audio, input, etc., without putting Unity APIs inside core services.

It is aimed at games that want JSON-tunable balance and content (boons, consumables, shops, scaling) while keeping game-specific simulation (board, world, combat loop, etc.) in your own code that talks to the engine through events and/or a dedicated service.

When it is a good fit

• You want one place for save-shaped data and run-shaped data, with clear lifecycle (new run vs continue).
• Designers or tools edit JSON (rules, definitions, invocations) more than C#.
• You are OK reading C# for behavior that is not expressible in data (new service, new adapter, new event types).

When to look elsewhere or keep code minimal

• You need no shared service layer—only a small game might not justify the indirection.
• You dislike stringly-typed service ids and event ids; the engine leans on conventions and JSON.

Key types (for navigation)

Next: Unity host & runs for how lifetimes map to Play Mode.