The goal of Diamond Mine is to collect as many diamonds as possible from 20 underground shafts. Each is presented as a single screen with corridors and alleyways. Monsters are released at intervals from a Pacman-style hub, these can be shot. The mines are covered in dust initially, until you have walked through an area, a bullet can't be fired through it. Contact with a monster loses all your gems, so the best strategy is to shoot them out first - as most diamonds are down corridors, this can be planned for. You can start from one of 5 different screens.