Dev Builds CUDA Rigid-Body Simulator Handling 200K Bodies

On August 30, developer yacineMTB showcased a homegrown rigid-body physics simulator built on Box3D and running entirely on CUDA, supporting up to 200,000 concurrent rigid bodies with no MuJoCo involved. In the demo, a robot called Microduck walked with a lifelike, stable gait. He later confirmed the engine is deterministic and remains so even after adding the robot.

Confirmed

• The simulator is based on Box3D, runs entirely on CUDA, and does not use MuJoCo (m1/m3/m5/m6)
• Supports up to 200,000 concurrent rigid bodies (m1/m3/m5/m6)
• The Microduck robot achieves a lifelike, stable walking gait in it (m1/m3)
• The engine is deterministic, and stays deterministic with the robot added (m2/m4)

Why it matters

• High-concurrency simulation plus determinism means identical inputs yield identical results, ideal for massively parallel AI training and reproducible robotics experiments
• A pure-CUDA implementation shows a viable path for self-built physics engines independent of existing stacks like MuJoCo

2026-08-30 ~ 2026-08-30 · 6 related posts

• [source] Custom CUDA simulator supports 200k rigid bodies, runs Microduck — yacineMTB · 2026-08-30
• [source] AI Physics Engine Remains Deterministic Even After Adding Robots — yacineMTB · 2026-08-30
• [source] Demo: Deterministic Physics Engine Maintains Consistency with Robots — yacineMTB · 2026-08-30

3 near-duplicate retellings: eigenron · yacineMTB · AlpinistXBT