The Schemaverse (http://schemaverse.com) is massive multiplayer game that you play through programming, although the gameplay is no longer persistent and is now played in one day rounds. I would love to make a better persistent version one day but it needs a lot of hardware to support most users complete lack of optimization (or deliberate resource hogging attacks).

Schemaverse isn't nearly as polished as this is but if you are looking to battle some AI, give it a chance.