Thanks for checking it out. I do plan on improving them by using the list of moves that I record...I am thinking of making a Robot API or something too...but it's hard to be motivated to improve them too much when a large majority of people lose to Rex. This also makes the idea of finding the best move out of the moves that have occurred flawed (for now anyway) too.
Rex pretty much prioritizes getting a 'second move'. I've yet to see him protect against a capture.
Yeah, all he is capable of doing is finding an extra turn then it's basically pick one at random. Although, there's a bit of randomness mixed in. There's about a 1 in 6 chance that he will basically become a higher level robot on a given turn.