Developer

Building on Washiki Washoi. Architecture overview + how-tos for the common extension points.

Architecture at a Glance

Three things to understand before extending:

1. The server is authoritative. All gameplay state lives on the server. The client predicts locally for responsiveness, but the server's tick is the source of truth.
2. The simulation is shared. simulation/FPSSimulation.ts runs on client (predicted) and server (authoritative). Identical code, identical config. Drift between them is a bug.
3. The engine seam. The submodule talks to the engine through documented extension points: NetworkConnector, GameplayMapLauncher, Pickup (subclass), CommandRegistry, IGameHost. See getting-started/project-structure.md for the full mapping.

How-Tos

Page	Covers
Adding a Weapon	Defining a new WeaponDef, projectile, HUD slot
Adding a Gametype	Subclassing BaseGametype, score/time rules, registration
Server Commands	Op commands for dedicated server admins

Code Conventions

• Singleton pattern throughout. XYZ.getInstance(). Reset hygiene matters — use resetInstance() in tests.
• EventBus for decoupled events. Always store unsubscribe handles.
• No Game.initializeLocal. Everything goes through NetworkGameHost now (since v0.9.15 in the engine). Single-player runs a real dedicated server in-process via the lobby's dev-spawn — see the engine's Map Launching Guide (docs/manual/guides/map-launching.md in the engine repo).
• Submodule edits commit to this repo first, then the outer engine repo bumps the submodule pin. AGENTS.md in the engine repo documents the flow.

Tests

Tests live in __tests__/ directories next to the code they cover. Run from the outer engine repo:

npm test           # all tests, including submodule
npm test FPSPickup # filter by name pattern

The outer vitest config picks up src/games/fps/**/*.test.ts automatically.

See Also

• The engine's Service Registries (docs/manual/guides/service-registries.md in the engine repo) guide — how to add new engine→game injection points
• The engine's Pickup System (docs/manual/guides/pickup-system.md in the engine repo) guide — Pickup base class hooks