Box3D, an open-source 3D physics engine, is now available on GitHub as a fork of Box2D with 3D extensions. The engine adds triangle mesh collision, height-field collision, and baked compound collision to address gaps in existing solutions.

The developer created Box3D while building The Legend of California at Kintsugiyama, encountering problems with Unreal's Chaos physics system. Chaos lacked gyroscopic torque simulation and produced erratic tree-falling behavior, critical issues for survival gameplay with hundreds of thousands of server entities.

Box3D powers survival mechanics like tree chopping with custom broad-phase optimization for massive entity counts. It's already adopted by Facepunch Studios' s&box platform, Esoterica engine, and a 1000-player multiplayer game.

As an alpha project approaching v0.1 release, Box3D offers a viable alternative to proprietary physics middleware for developers needing custom physics behavior.