In this version of the game, more than two colors can play, and the board can have any topology (i.e., not just a regular grid). However, the same simple rules from the original game still apply: no group may remain on the board unless it has liberties, and no board state may be repeated.
The game also includes an AI. However, since the AI was written to work with boards of any topology it can't use specialized knowledge about joseki, etc. In other words, don't expect too much from it on a 9x9 or 19x19 grid!