Phyz (Dax Phyz) is a public domain, 2.5D physics engine with built-in editor and DirectX graphics and sound. In contrast to most other real-time physics engines, it is vertex based and stochastic. Its integrator is based on a SIMD-enabled assembly version of the Mersenne Twister random number generator, instead of traditional LCP or iterative methods, allowing simulation of large numbers of micro objects with Brownian motion and macro effects such as object resonance and deformation.