The rules are pretty basic. You swap blocks next to each other and try to line up three or more of the same color horizontally or vertically. This makes Rockman attack his opponent, and you beat the opponent when their life gauge reaches zero. As an added feature, although it's not explained in great detail, Rockman can gain special weapons from his defeated opponents and use them to cause various effects in puzzles.
Of course, this is just a simple puzzle game that could have any characters slapped onto it, but I'll say it anyway; Japan gets all the cool Rockman stuff!
News Credit: CAP Kobun