I did something very similar to this for an artificial life class back in college. My nets took significantly longer to learn how to race for some reason, but i

I did something very similar to this for an artificial life class back in college. My nets took significantly longer to learn how to race for some reason, but in the end it worked out. What I did was start off as simple as possible, just using a circular track so that it's easy to test bounds on the inputs (position greater than inner diameter and less than outer). My nets would get their sensor inputs at each time step, and would output a steering angle and speed. The speed would basically just be directly added to their current position after pointing them in the chosen direction. The fitness function amounted to seeing which racers got around the track the fastest. You can get some pretty interesting behavior if you start with a barebones model of the world like that. At one point my racers started teleporting around parts of the track by taking advantage of the fact that I wasn't doing continuous collision detection - they would detect a turn and then output a speed and direction that would cause them to instantly appear on the other side of the corner without navigating the curve on the way. It was interesting to watch them balance the ability to teleport against the range of their sensors. This sort of thing really lends itself to incremental tinkering, especially with javascript as powerful as it is today for prototyping. That gives a lot of intermediate feedback that will give you chances for finding new strange things to investigate. Adding features like tricky track generation is a decision you can make along the way if it seems interesting.