Building in the open

Open Terrain Engine is an AI-native, native-desktop game engine where an LLM agent authors a complete game in idiomatic, human-editable C# — and verifies it through a deterministic, headless loop. It's in active development: the design is complete, and we're building it now.

This devlog is where we'll show that work as it happens — the decisions, the milestones, and the occasional wrong turn.

Why build in public

The hard part of an AI-native engine isn't the rendering or the netcode; it's the loop the agent works in. Getting that right is iterative, and a lot of the interesting detail lives in the why behind each choice. Writing it down keeps us honest and gives anyone evaluating the engine a real view of how it's coming together.

What you'll find here

• Engineering notes — how the determinism spine, the verification contract, and the genre-general systems actually get built.
• Milestones — when something real starts working end to end.
• Decisions — the trade-offs we made and the alternatives we passed on.

A taste of the thing we're really building — the agent authors C#, then proves it:

var snapshot = Sim.Simulate<FallingBox>(seed: 7, frames: 10);
Assert.Equal(Fix.Zero, snapshot.Single<Position>().Y); // landed at y = 0

More soon. If you want to be there when it ships, the waitlist is the place to be.