Make the engine yours.

Orrin is an open-source 3D engine written in Rust, with C# scripting hosted in-process. It's built so you can take the subsystems your game needs and leave the rest behind.

Get started View source
  • Rust core
  • Vulkan via vulkano
  • C# via CoreCLR
  • GPL-2.0
quick start 
# Run the engine on its built-in demo
$ cargo run -p orrin-core

# Or scaffold a project with the CLI
$ cargo build -p orrin-cli
$ ./target/debug/orrin new my-game

The editor

Early demo state, expect changes.

The Orrin editor: an entity hierarchy on the left, a viewport rendering a grid of textured cubes and reflective spheres under an HDRI sky, environment and shadow controls on the right, an inspector for the selected cube, and a console logging scripts rebuilding and reloading.
The editor, mid-session

Only the engine you actually use

Most engines are generalised, so every project carries the weight of every feature. Orrin's position is the opposite one: select the options your game needs, and don't get held back by the rest.

See what's shipped
Scope 3D first. 2D is planned for the future, not shipped.
Modularity The fit-to-purpose feature system is tracked as issue #59, in Phase 5. Not shipped
Licence GPL-2.0. Full source, editor included.

Two seconds, or it's a regression

Unreal's compile-and-restart loop and Unity's domain-reload stalls are the most-complained-about parts of both engines. Orrin treats “change code, see the result in under two seconds” as a hard constraint every subsystem has to respect - game code, shaders and assets alike.

Read about scripting
Orrin's Scripts panel reading “Build up to date (0.8s)”, with “Reload after a successful rebuild” ticked and one behaviour attached.
The build watcher, after a 0.8 s rebuild

Hot reloading and external game assemblies landed in Phase 2 (issue #5); the build watcher is issue #18.

Nothing here should need our servers

Licensing changes, runtime fees and closed editors are the reason people stop trusting an engine. Orrin's rule is that no subsystem may ever depend on a service only the Orrin team can run. Anything networked has to be self-hostable, with paid hosting as a convenience on top.

The longer argument
Source Full source including the editor, under GPL-2.0.
Servers The collaboration server, registry and build cache are all planned as single self-hostable Rust binaries.
Rule The hosted version must never do anything the self-hosted one can't.

Where the project actually is

Phases 1 and 2 are largely closed: C# scripting, hot reload, external game assemblies, the CLI and the build watcher all landed. Phase 3 (editor usability and the asset pipeline) and Phase 4 (shadows, lights, audio, in-game UI) are the open work.

Real-time collaboration and the package registry are named in the architecture plan for 2027–2028. They are not implemented, and this site doesn't pretend otherwise.

Contributions aren't open yet - the plan is to accept them after Phase 5. Until then, the Discord is where development gets discussed.

Start with the demo scene

One cargo run gets the engine up with its built-in demo. The CLI scaffolds a project with a manifest, a .csproj and an entry Behaviour, so you don't have to know the workspace layout first.

Get started