v1 beta three.js editor + substrate · $2.99

An editor for the
game your AI wrote.

Your agent can one-shot a three.js game. It can’t tune one — every pass at feel is another prompt, a few thousand more tokens, and a rewrite of something you already liked. DevTune hands you the dials: change the number, press K, it lands in your real source.

PhysicsRapier, already right. Contacts honest, collision shapes matching the art.

MovementA character controller your agent doesn’t have to invent at 2am.

CameraA follow camera that already works.

AddressesEvery number knows its own line — src/world.js:count. This is the part nobody else has.

GatesVerify, smoke and doctor. Your agent can’t call it done; they decide.

The deskPress C mid-game. Click anything, move it, drag its numbers. Nothing restarts.

SavePress K. It’s written into your real source, on the line it came from.

Get it — $2.99 One prompt. Your AI installs it. You never open a terminal.

Tokens to tune

Dragging a slider doesn’t call a model

Re-prompts for feel

Nothing you liked gets rewritten behind your back

Accounts

No sign-up, no licence server phoning home

Uploads

Nothing leaves your computer

Made by one person — hi, I’m Gino. three.js only, not Unity or Godot. Works with Cursor, Claude Code, Grok and Codex — same paste.

v1 beta What that means, exactly

This is version 1 of a three.js editor and substrate built by one person, and it is still moving. Updates ship as they land — you get them with npx devtune@latest, at no extra cost, forever. There is no subscription and no upgrade price.

What already works is listed above and is what you are paying for. What’s next is decided largely by the box below.

Found a bug? Want something it doesn’t do?

Tell me. I read every one of these and they set what gets built next — most of what shipped this month came straight out of somebody using it and saying what was wrong. You don’t need to own it to send one.

Send feedback Request a feature

Bugs: what you did, what you expected, what happened. Raw is fine.

Questions

Do I install anything myself?

No. You paste one block and your AI runs everything. You never open a terminal.

Which AI?

Any coding agent that can run terminal commands — Cursor, Claude Code, Grok, Codex. Same paste for all of them.

Unity or Godot?

No. DevTune is three.js only. The physics, movement and camera are built on three.js and Rapier directly, so it isn’t a port waiting to happen.

Does it need the internet while I’m working?

It installs from npm once. After that the editor runs entirely on your own machine. No account, no cloud, nothing leaves your computer.

What if a command fails?

The prompt tells your AI to stop and show you the full output instead of working around it. Send me that output.

Does it work on a game my agent already one-shot?

Partly. Attaching to a game that’s already written, I can usually reach about one number in six. Built with DevTune in it from the first prompt, I reach all of them. If you’ve already got a game you like, point your agent at it and have it remould the game through DevTune — that’s a rebuild, not an attach, and it’s what the prompt tells it to do.

Does my agent need to know DevTune already?

No. The prompt gives it everything — the rules, the packs, the checks. It reads them at install. Nothing to learn, nothing to configure, no MCP server to wire up.

Can I still ask the agent for changes afterwards?

Yes. DevTune isn’t a lock on your code — it’s ordinary source files your agent can keep editing. What it removes is the need to re-prompt for feel, which is the round trip that keeps breaking things you were happy with.

It says v1 beta — what’s missing?

Nothing that’s listed on this page — everything above works today and is what you’re paying for. Beta means it’s one person’s version 1 and it’s still moving: rough edges get found and fixed weekly, and the roadmap is set mostly by what buyers report. If you want a finished, frozen tool, wait a few months. If you want to shape one, now is the useful time.

Do updates cost extra?

No. npx devtune@latest and you have the newest one. No subscription, no upgrade price, no version you get locked out of. You bought the tool, not a year of it.

How do I report a bug or ask for a feature?

The box above the questions — it’s the fastest way to reach me and I read all of it. For a bug, the useful three lines are: what you did, what you expected, what happened.

Refunds?

Yes, for any reason. Message me on the project page within 14 days and I’ll refund it — no questions, no form. It’s a v1 beta at $2.99; if it isn’t for you, it isn’t for you.

You’re in.

Copy the prompt, paste it into your AI. That’s the whole install — nothing to fill in.

The prompt

You are installing DevTune into this project.

1. Run exactly:
   npx devtune init
   npx devtune doctor

2. Read the files it wrote under .devtune/ai/ (or print the paths from init).
3. Build or remould this game so it is born-owned — contracts and packs.
4. Run: npx devtune verify && npx devtune smoke && npx devtune serve --shell
5. Tell me the local URL. I will edit the game and press K.
6. If any command fails, stop. Do not work around it.
   Paste me the full output of the failing command.

Cadence for long builds (hours):
- After every build chunk: npx devtune verify
- About every 30–60 minutes: npx devtune verify && npx devtune smoke
- Never delete or skip doctor/verify/smoke to stay green
- Do not add a second physics engine

copied

Your key — keep it, you don’t need it

—

copied

Proof of purchase, nothing more. There’s no account and no licence server for it to be checked against — adding one would mean this tool phoning home, and it never does. Quote it if you ever need support.

Then

Open Cursor, Claude Code, Grok or Codex → start a new agent chat inside your game project → paste. When it gives you a URL, open it and press C.

Save this page. The same key and prompt are in your email receipt.