PhysPix is a 2D physics simulation framework that works exclusively with pixels. Modern physics engines can process collisions rapidly and efficiently by leveraging geometric information, but artists wanting to work with pixel-based content are required to map each pixel-based object into the geometric primitives that are understood by these systems. Effects such as terrain destruction then require remeshing, which can be onerous to perform at runtime. The alternative is pixel-perfect collision handling, but past games that use this approach have not attempted true rigid body simulations. To address this problem we developed PhysPix, a 2D rigid body simulation framework based on pixels. PhysPix allows 1) artist control over the exact boundaries used for objects in the simulation, 2) natural bitmap-based support for destruction, and 3) an intuitive painting interface for properties such as non-uniform weight distributions.