In college I enjoyed participating in a few AI competitions. Students would develop some basic AI for a robot who could move and shoot, submit the code and then watch everyone's robots battle on a large projector in a digital arena. Very educational and fun.
I know there are many open source projects that let you build and compete in these sort of things, but they always seem to be language specific. You can't battle your Java AI against your C# or Python AI. So, what if we all settled on a common language such as JSON & REST? And what if we made the game persistent?
The idea is this. A cloud hosted game which is persistent but allows new players to join or leave at any time. To participate you only need to register an account and give it a base URL of where you are hosting your player's AI logic. There would be some documentation on the expected REST URLs that need to be available. This lets you use any language you want to participate. It also allows players to have a database to store past moves or data about the environment. The game server could manage invoking the player's AI based on a turn system or in real-time when needed. A player's AI while waiting for a 'turn' could invoke service calls on the game server to 'look around' and learn about the environment.
The visuals would obviously be basic at first and should be displayable on a webpage.
The game itself could be as simple as a 'player' moving and shooting when it detects another player. You could introduce items, weapons, etc.
Or it could be more complex and similar to this (posted on HN not too long ago):
http://phonons.wordpress.com/2010/06/01/cells-a-massively-multi-agent-python-programming-game/
Does something like this exist?
(For example, in a beautiful simulation where a single program had to control a colony of ants who did not have any room for state other than a current instruction pointer and the input of their senses, someone successfully identified an algorithm to have each ant figure out which ant they were, and then execute a pre-planned sequence of moves to wall in the entire enemy base, faster than any non-degenerate program could possibly counteract it. It was beauty to behold but it also crushed the life out of the community -- the best ant has been crowned, everyone else gets to play for second best.