theaigames.com does this by running the game engine and bots as console apps and communicating by sending simple commands through their input and output streams

theaigames.com does this by running the game engine and bots as console apps and communicating by sending simple commands through their input and output streams. They generally provide some "starter bots" for a couple languages, in which the message parsing is already handled for you, but they accept bots in any language.