Press start evolution over at the right. Scroll down for a description. See the code to evolve your own.
Works by contracting "muscles"
Speed controls how fast the simulation progresses
Creature is how the creature should look
Mutation chance the chance of some muscle having its contraction characteristics changed
Crossover chance the chance of two parents being mixed
Population size how many creatures there should be
Inspired by this video by Junior Rojas, Boxcard2d and its browser predecessor Genetic Cars 2.