Warning: This thing breaks easily. Use it gently.
Evolve button starts the genetic evolution. After the first 3 generations a graph of best fitness and average fitness will be shown over this text (actually it's not the fitness: it's the food eaten by robots, so it should raise with generations). To stop the evolution, press the stop button, even if it seems unresponsive, it will stop the evolution after finishing current generation.
Simulate button starts the visual simulation. It must be only used after the first generation, and when the evolution is stopped, and when there's no simulation running. Otherwise, things may blow up.
Simulation stops itself after some time without further notice. Then, you can start it again.