K.O ! is a wacky action / dexterity game. Two gadgets are set in a groove in a heavy duty plastic board. Each gadget has a handle, a hammer (which can be operated through a button on the handle) and a tube filled with 5 discs. The tube has two horizontal slits at the bottom. By sliding your gadget along the groove you try to strike with your hammer through one slit, thereby hitting a disc of your opponent and send it flying. When you lose your last disc you're knocked out. It's a matter of speed and reaction. Even when sliding your gadget all the way forward, your hammer may not reach the tube of your opponent. So you've got to feint, lure your opponent forward, strike fast and be quick to retreat.