Your first fighter will be waiting behind the trap door. As he enters, the door closes behind him. Now all he can do is work his way through the maze and shoot the monsters before he gets killed (which is inevitable, since there’s no way out). He has a limited supply of bullets, so it’s necessary to pick up a new gun now and then. Spiders will paralyze him, the blob will steal his bullets, and the robots will just try to kill him. Shooting a yellow robot earns you another fighter. – Atari Guide