Cambrian Explosion is described as 'The primary focus is to evolve locomotion in a variety of creatures using a genetic algorithm in a fun easily accessible simulation allowing to understand the fundamentals of evolution. Stay tuned. More to come :)'. There are four games similar to Cambrian Explosion for Online / Web-based, Windows, Linux and Mac. The best alternative is Genetic Cars 2, which is both free and Open Source. Other Cambrian Explosion like games are Biogenesis (Free), BoxCar 2D (Free) and Egg Worm Generator (Free).
The program uses a simple genetic algorithm to evolve random two-wheeled shapes into cars over generations. Loosely based on BoxCar2D, but written from scratch, only using the same physics engine (box2d).
The program learns to build a car using a genetic algorithm. It starts with a population of 20 randomly generated shapes with wheels and runs each one to see how far it goes. The cars that go the furthest reproduce to produce offspring for the next generation.