WCK (World Construction Kit) is an ActionScript 3 physics engine built as a port of Box2D (with Flash Alchemy in mind). It provides tools for building simulated worlds with rigid bodies, shapes, collision detection, joints, gravity, etc., embedded into Flash/AIR environments. It aims to integrate Box2D-style physics decently with Flash, allowing developers to assemble physics scenes (“worlds”), define shapes, manage simulation steps, and run demos.