Karate Champ, for those of you who don't remember seeing it in the arcade way back when, was the original 1 vs 1 side view fighting game. Just imagine Street Fighter, but with no buttons, no special moves, no characters, and no story. Don't feel sorry for Karate Champ though, it has a lot going for it, you just have to put yourself in a retro time warp.
The game works extremely simply, with two four directional joysticks and no usable buttons. The left joystick moves you and the right joystick does all the punches and kicks. Using the joysticks together makes you do more moves (think jump kicks), but these moves are a bit tough to pull off.
The trick to the game is that instead of being an all out slugfest, Karate Champ is like a real karate competition in that the first person to get a clean hit in wins. Because of this, you have to block when punches come in, duck when high punches come, and jump over low kicks. You have to think like the enemy in order to win, and in most cases, guessing the next move a computer is going to make it rather tough. Fortunately, once you have had enough of beating up on the computer (no easy task, the computer gets really hard really fast) you can beat up on your friends via bluetooth or WiFi multiplayer.
Overall, the game is much more about retro gaming relived than a good new gaming experience. If you hadn't played the game at all in the past, you probably won't be too interested in this version. The controls are a bit tough because of the joystick layout, but they are certainly workable. Just try to think of the good ol' days when you would mindlessly sit in front of your Atari thinking "man, is this great or what!".