Platformer multiplayer browser game template for Net Forge, the open-source multiplayer browser game engine built for AI coding agents.

This is a template for a platformer that runs in the browser: SKYLEDGE, a complete multiplayer game you can start in one command and change in one file. A side-view platformer race: up to eight climbers race along cliffside courses to the flag, with tuned jump feel and seat bots that run planned routes.

What you get

• Up to 8 players per race, and seat bots that fill the empty places.
• Coyote time, jump buffering, variable jump height and an air dash.
• Springs, one-way ledges, moving platforms, thorns and per-player coins.
• An authoritative room at 60 Hz with your own climber predicted in the browser.
• Authoritative multiplayer. A room host owns the game state; every browser tab is a player. Locally, npm run play runs that host on your computer.
• Shared client/server simulation. The same ECS and Rapier physics code steps the world on the server and predicts your own player in the browser, with delta snapshots.
• three.js renderer with WebGPU, and a WebGL2 fallback.
• Bots and a headless playtest. npm run test plays the game with bots and reports what happened.
• TypeScript, MIT licensed. The library models, sprites and sounds the game uses are CC0.
• Ready for coding agents. AGENTS.md, CLAUDE.md, Cursor rules, Copilot instructions and the Net Forge MCP server in .mcp.json, .cursor/mcp.json and .vscode/mcp.json.

Measured with npm run test (2 bots, 1 minute of game time, Node 22, Apple M2 Pro):

Playtest report	Value
Ticks simulated at 60 Hz	3,600
Races won	2
Share of bots that finished	100%
Earn rules fired (play money)	13
Server cost per tick (mean)	under 0.25 ms
Softlock	none

Every number above is play money and a local run. Longer runs: npm run test -- --minutes 4 --bots 4.

Start in one command

npx create-netforge my-game --template platformer --yes
cd my-game
npm run play

Or press Use this template on GitHub, clone your new repository, and run:

npm install && npm run play

npm run play builds the game, starts a local room and opens http://127.0.0.1:4663. Open the same link in another tab for a second player. A D or arrows to run, Space W or Up to jump (hold for height), Shift to dash, Down plus Jump to drop through a ledge, R or Enter to ready the next course.

You need Node.js 20 or newer. Use npm run play -- --no-open to print the link instead, --port 4700 if the port is taken, and --host 0.0.0.0 to let phones on your network join. Local play uses play money: no wallet, no chain and no hosted servers.

Change the rules

The whole game is src/game.ts: declarations against the typed API in @netforge/engine (the only import it may make). The template package @netforge/template-platformer provides the renderer, netcode, physics, controls, HUD and bots.

npm run test        # compile src/game.ts and play it with bots; fails on a broken rule or a softlock
npm run typecheck   # the TypeScript check of src/game.ts
npm run play        # play the change (stop and start it again after each edit)

The template guide walks through the usual changes:

• Build a course
• Tune the jump feel
• Reward a clean climb
• Check it with bots

llms.txt holds the rules the build enforces and recipes for common changes. Or ask your coding agent in plain words; AGENTS.md tells it where the rules live and how to test them.

Links

• Template guide: https://forge.netnet.capital/docs/templates/platformer
• Net Forge engine: https://github.com/netnetdev/net-forge
• Docs: https://forge.netnet.capital/docs
• npm: create-netforge, @netforge/template-platformer, @netforge/engine

Pinned to Net Forge 0.2.0. Not affiliated with other projects named NetForge. Local play runs the game's own code on your computer with your permissions; play only games whose code you trust.

License

MIT (LICENSE). The library assets are CC0 1.0.