You (as a karateka) fight a series of combats in various locations of the world (simply changing the landscape you see; they do not affect gameplay).
If you defeat your opponent, you go on the next stage. If you are defeated, the game is over (you have to restart all from the beginning).
You score points based on the moves you use to hit your opponent and how much time overall you need to win the match (the fewer, the better).
A few very short mini-games of karate related feats offer a small diversion between the matches.