Janus Engine

Key facts: Janus Engine, from Rad Games, packs 18 game-making tools into one browser tab with zero installs: a deterministic Rust core that holds the truth, plus AI cognition that makes worlds react and remember, joined by one audited gateway. Every AI tool is also a REST call and an MCP tool, so Claude Code or Cursor can make sprites, music and voice lines straight into your project. It powers Rad Games titles Puppies vs. Kittens and RiftBleed, and everything you make is yours.

Plans: Browser tools are free and unlimited; AI tools spend credits, with 100 free credits and no signup needed for Studio.

Best for: Indie game makers who want art, music and voices without installing a toolchain. Who should skip it: studios that need a full 3D engine rather than asset tools.

Pros

• 18 tools in one browser tab, zero installs
• Every AI tool is also a REST call and an MCP tool for Claude Code or Cursor
• Powers real shipped Rad Games titles, not just demos
• Everything you make is yours, with 100 free credits and no signup for Studio

Watch out for

• Asset tools, not a full game engine: you still need somewhere to build the game itself
• AI credits run out, and heavy asset generation will need more
• A newer studio ecosystem, so community tutorials are thinner than for big engines

Best for

Indie game makers who want sprites, music and voices without installing a toolchain. Who should skip it: studios that need a full 3D engine, or teams with an established asset pipeline they do not want to change.

Pricing

Browser tools free and unlimited; AI tools spend credits, with 100 free credits and no signup for Studio.

FAQs

What is Janus Studio? A browser tab with 18 game-making tools, running on the Janus Engine's deterministic Rust core plus AI cognition.

Can my coding agent use it? Yes, every AI tool is also a REST call and an MCP tool for Claude Code, Cursor or any MCP client.

Do I own what I make? Yes, everything you make is yours.

Is there a free tier? Browser tools are free and unlimited; AI tools come with 100 free credits and no signup for Studio.