You need to place stones on empty places and directly enclose horizontally, vertically or diagonal opponent stones between one of your stones and the new one. You can change the enclosed stones of your opponent into your color. The winner is the one with more stones at the end of the game.
Very simple rules, but a challenge to play!

Installation:
You only have to extract the downloaded zip file and to copy the version you need (ARM, XScale, SH3 or MIPS) to your PocketPC.