1 · React reference harness
In-browser lobby built with React. Sign in as a guest, host a room, copy the share link, watch members join in real time. The protocol's first proving ground.
Open harness →
Multiplayer dev tools
New here? /dev/build is the orientation page (mental model + traps). Then come back here for the tools.
Five ways to exercise the b3.games multiplayer stack. See the contract spec (AI-optimized in-app version, card #5) for the rules every multiplayer game adheres to.
2 · Lobby-only reference
Smallest possible MP game (mp-ready-check) — member roster + ready toggle. Different visual style than #1 on purpose — proves the contract is style-agnostic.
Open game →
3 · Determinism reference
Exercises the full B3Multiplayer contract (mp-moving-rect): two players push a rectangle with arrow keys, lockstep across all clients. Uses ctx.random + ctx.math.cos; no native Math inside tick.
Open game →
4 · Contract validator
Paste a game's HTML to get a per-rule report. Catches missing meta marker, SDK import, required SDK calls, UI elements, mobile breakpoints, touch-target sizes. Diagnose-only (no auto-fix).
Open validator →
5 · Contract spec (AI-optimized)
Canonical URL to hand to a Claude Code session along with your single-player HTML game. TL;DR skeleton + 5-function table + ctx surface + forbidden APIs + 3 genre examples + self-test snippet.
Open spec →
6 · 3-layer template (Solo + MP)
First cross-runtime reference (mp-game-template): start screen → host/join lobby → coin-collector gameplay. Loads BOTH /mp-client.js and /mp-runtime.js. Demonstrates the 3-layer pattern the rewritten contract leads with.
Open template →