Build anything at the speed of thought. 100% Rust.
Zero compromises.

Games, simulation, data, and the internals: same engine, same cards, one panel.
Bevy's PBR pipeline. Real-time lighting, shadows, atmosphere, reflections. Worlds that look shipped, not prototyped.
Procedural terrain and seamless streaming. Walk for hours and never hit a loading screen.
QUIC networking, server-authoritative, low latency. Built in, not bolted on.
OpenXR out of the box. Quest, PSVR2, and desktop XR from one project.
Avian physics with soft bodies, ragdolls, and things that break the way they should.
One project, every screen. Windows, Mac, Linux, mobile, web, and headset.
Sound that lives in the world, not just the speakers. 3D positional audio, occlusion, and reverb that track the geometry.
Fire, smoke, sparks, and spells. GPU particle systems that hold their frame rate when the screen gets loud.
Honest, category by category. We do not win every row. We will show you the ones we lose.
| Capability | ||||
|---|---|---|---|---|
| Real-time 3D world | β 60+ FPS | β RTX | ~ Basic 3D | β Plots only |
| Scale (entities) | β 10M+ | β Large (USD) | ~ 100Ks agents | ~ Matrix-bound |
| Time compression | β ~1 yr/sec | ~ Limited | β Discrete-event | β Numerical |
| Agent-based modeling | β ECS-native | ~ Via Kit | β Specialty | ~ Toolbox |
| Numerical / control libs | ~ Growing | ~ Partial | ~ Partial | β Gold standard |
| Photoreal rendering | ~ PBR | β RTX path-traced | β None | β None |
| AI-native control | β MCP bridge | ~ Kit/USD | β None | ~ Scripted |
| Source open / forkable | β PolyForm Shield | β Proprietary | β Commercial | β Commercial |
| Pricing | β Free, no royalty | ~ Free indie, paid ent. | β $$$ license | β $$$ per seat |
| Feature | ||||
|---|---|---|---|---|
| Performance | β Native Rust | ~ Lua VM | ~ C# + Mono | β C++ |
| Memory Safety | β Guaranteed | β Sandboxed | ~ GC Pauses | β Manual |
| Max Instances | β 10M+ | ~ 100K | ~ 500K | β 1M+ |
| Web Export | β Native WASM | β None | ~ WebGL | β Limited |
| Source open / forkable | β PolyForm Shield | β Closed | β Closed | ~ Source access |
| Pricing | β Free, no royalty | ~ Revenue share | β Per seat | ~ 5% royalty |
| Scripting | β Soul + Rune + Luau | β Luau | β C# | β Blueprint + C++ |
| Studio Editor | ~ Maturing | β Polished | β Polished | β AAA |
Game-grade 3D meets real physics and real data. The simulation does not cheat, and it still runs at interactive FPS.
PolyForm Shield means no platform tax, no royalty, and a roadmap you control. Fork it, ship it, keep the work. The one limit is reselling the engine itself.
Drive the live engine over MCP. An agent can build a scene, run a year of consequences, and read back the result.
Real models running in the engine today
Anode-free lithium-sulfur, 569 bipolar layers in one can: 1,223 V and 1,032 Wh/kg, aged 699 cycles in seconds
Source-available, top to bottom. The clock, the physics, the data layer, all of it readable under PolyForm Shield. If a claim on this page matters to you, go read the source.
Memory safety is structural, not aspirational. The bug that eats other teams' weeks does not compile here.
Not a render. Thousands of entities, interactive frame rates, click-select and raycast. A real engine you can launch right now.
The best simulation engine should not be a walled garden. It should be free.
Eustress ships under PolyForm Shield: free to clone, fork, and build on. The work you put in is the equity you keep.
Join the builders simulating reality, and owning every bit of it.
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