Genex wraps Claude Code and Codex in an MIT-licensed harness for Three.js games

A session starts with a plain description of a game or a feature. Genex then splits the work: one model plans, other agents build, and visual judges inspect the result ^[3]. Users can pick a different model for each of those roles ^[9]. While the run is underway, the desktop app shows the workers changing code, checking builds and taking feedback from the human ^[4].

The model plumbing is what I would check first. Genex says the app runs on existing Claude or ChatGPT subscriptions and does not need API keys ^[10]. That makes setup cheap. It also moves the ceiling to the plan's usage limits. Runtimewire notes that those limits, or the cost of local compute, stay with the user ^[16].

The project format is the strongest choice Genex made. Genex calls the software a customizable harness for game development and says it is not a new engine ^[2]. Its public GitHub repository bears that out: each project is a normal Three.js codebase written by the coding agent, with Genex adding tools for assets, multiplayer and publishing ^[12]. Files stay on the user's computer ^[5]. A finished game exports as a static web bundle or publishes through Genex ^[6]. Walk away from the harness and the repo is still a Three.js project a developer can open and keep working on ^[22]. GDevelop, by comparison, pairs its own engine with an AI agent that edits projects inside GDevelop's editor, according to Runtimewire ^[17]. Rosebud AI takes a plain-language prompt to a playable game in the browser ^[17].

The self-editing mode is experimental and off unless the user enables it ^[14]. I would not ship an agent that rewrites its own instructions with any other default. When it is on, prompts, skills and tools live in a Git repository the app can edit ^[13]. The app takes a snapshot before a change, and a blind judge compares the result ^[13]. A version that fails to start is rolled back ^[13]. Keeping that history in Git means a person can read what the agent changed as a diff afterward ^[23]. Startup is the only automatic rollback condition in Genex's description. A revised prompt that boots cleanly but makes the builder worse has to be caught by the blind judge's comparison ^[21].

Assets come from Blender for local 3D modeling and Meshy for generated models and characters, and the app accepts custom plugins and skills ^[11]. Per Genex's product page, the desktop app is free under the MIT license, and the paid component is optional asset generation through a Genex plugin ^[15].

Scope is narrow for now. The app targets Three.js games that run in a browser ^[6]. Unity and Unreal integrations are planned but not in this release ^[8]. The product page still lists Windows as coming soon ^[7]. In the launch thread, the makers said Codex is already part of how they build games, and that they wanted a harness of their own for combining models, tools and workflows ^[18]. Runtimewire frames the open test as whether the multi-agent loop can dependably build and verify useful Three.js games while the developer keeps control of the project ^[19].