You are Warmonger and with your fellow inmate, Mandroid (played by a 2nd player at the same time) you plan to escape this maximum security prison orbiting Earth. As the prisons on Earth are full, Space Stations were built to house criminals like yourself. You have managed to arm yourself with a gun (Mandroid, a laser) and so you attempt to get past waves of guards coming towards you by avoiding or shooting them. If you can get to the end of the prison there will be a Space Shuttle waiting to take you to freedom. Occasionally a guard will appear carrying a rocket launcher which you can take if he is killed. This will kill multiple guards but only has a limited use. Touching a guard won't kill you just their bullets which leads to the loss of a life. Be careful with the gaps in the platforms as well as you will also lose a life if you touch the edge.

UCM: Ultimate Combat Mission is a Run 'n Gun game where you view your player from a 3rd person perspective at a high angle. You move vertically upwards with the screen scrolling as you move. The waves of guards come down the screen. As well as the main playing area you can also see your scores, lives and a ammo gauge for the rocket launcher.