Also, I made some student code a similar game a few years ago, cf my web page [1]. Except the game was played over IRC (the code was an IRC bot).
They had a working implementation in Racket and it was quite fun to play with. I don't think they released it however :-/.
EDIT: Actually I just asked and they did release it! But it's on Gitorious [2]…
See also: http://calvinandhobbes.wikia.com/wiki/Calvinball
That's what I was going to link to.
Also, I made some student code a similar game a few years ago, cf my web page [1]. Except the game was played over IRC (the code was an IRC bot). They had a working implementation in Racket and it was quite fun to play with. I don't think they released it however :-/.
EDIT: Actually I just asked and they did release it! But it's on Gitorious [2]…
[1] http://pablo.rauzy.name/teaching.html#ens-ispp_autonomic
[2] https://gitorious.org/autonomic