Loop Courier

A seeded transit-routing game about drawing one resilient delivery loop, then rewiring it while the city fights back.

Why it is interesting

• Every city is reproducible from a shareable ?seed= URL.
• Freehand and tap-built routes snap to stations and must connect a same-color pickup/dropoff contract.
• The courier moves continuously while packages expire, jams slow segments, and tolls drain score.
• Three mid-run two-opt splices let you rewire non-adjacent loop edges without resetting the courier.
• The whole game is browser-native: canvas, ES modules, and no runtime dependencies or external assets.

Play locally

npm ci
npm run dev

Open http://127.0.0.1:4173. No build step is required.

Controls

Action	Mouse / touch	Keyboard
Draw route	Click, tap, or drag; return near the first point to close	—
Start	Start	Enter
Splice	Splice, then choose two non-adjacent edges	S
Pause / resume	Pause	Space
Reset route	Reset Loop	R
New seeded city	New Seed	N
Tutorial	Tutorial	T
Fullscreen	Fullscreen	F; Escape exits

Circles are pickups, squares are dropoffs, and colors define delivery contracts.

Verification

npm run verify

The unit suite locks down seeded RNG output, deterministic city generation, route projection, and valid/invalid two-opt rewires.

For the real-browser smoke, run the server in one terminal and Playwright in another:

LOOP_COURIER_URL=http://127.0.0.1:4173 npm run test:browser

That smoke proves a complete seeded pickup → delivery, pause-time freezing, splice consumption, fullscreen/Escape, tutorial and modal actions, seed controls, and a 390 px touch layout. It also refreshes the showcase capture and writes inspection artifacts under output/.

For lower-level automation, the page exposes:

• window.render_game_to_text() — concise JSON describing the current interactable state and canvas coordinates.
• window.advanceTime(ms) — synchronous fixed-step virtual time for deterministic scenarios.

Deploy

All application URLs are relative, so the repository works from a GitHub Pages project subpath. The included Pages workflow publishes the static root on pushes to main; enable GitHub Actions as the Pages source in repository settings.

Project map

index.html              accessible game shell
style.css               responsive/coarse-pointer presentation
main.js                 game state, input, simulation, and canvas renderer
game-core.js            deterministic algorithms shared with tests
tests/                  core tests and replayable client choreography
scripts/                local server and browser smoke
assets/                 favicon and real gameplay capture

See CONTRIBUTING.md for extension ideas and CHANGELOG.md for release notes. Licensed under the MIT License.