[conflagration]

Halite also looks interesting, but I think with generals bot-makers will have much more possibilities, because there are no limitations for your implementation. The game mechanics might also a little more challenging in generals, especially the fog of war makes a huge difference imo.

[Analog24]

You'd be surprised how many implementation options there are in halite. People have come up with starter packages for just about every language you would ever want to use.