Sorry, my first post sounds much more critical than I intended. The thing is, I'm mostly interested in evolution sims and I was a bit disappointed to see that this part of the program didn't seem much improved. What I'd like to see would be vegetables that can evolve without predators (I.e. that can compete between themselves for something else than space), viable evolution for multibots, etc.
Anyway, the actual changes I'd like to make would mostly be to make the code read better, so that the logic becomes more apparent. Separate clearly what happens inside the robots from what happens outside, find a way to not use robots to make corpses and walls, etc.
Concerning the physics, the most obvious incoherence is that we have solid friction even though bots are supposed to live in water. Fluid friction (I.e. proportional to velocity) would make more sense. I haven't yet understood all the code, but it's written in such a way as to make me feel there must be mistakes. Perhaps there aren't, but rewriting it would make it is possible to understand and modify it.
PS: the version I have is 2.36.5, from the FTP server.