The Octoplex is a molecular prison used by the wizard Zolt to imprison anyone who has made him angry. You have been unfortunate enough to get on the wrong side of Zolt and so you have been sent to the prison but to make matters worse, he has turned you into some sort of hideous creature as well. Instead of accepting your lot and spending your remaining days trapped here, you have decided to escape. The only way to escape is to progress over various levels and fill the paths that make up each maze which are viewed from above and a small part of the level is shown on the screen and scrolls in various directions when you move.

To fill in a path you simply move along the paths but as you paint there are various creatures that roam each level and must be avoided or if you touch them you lose one of three lives. As you move about a level there are numbered gates blocking each path and you have to find and move over the same numbered switch to open and close them and there are also gates that open and close which can slow you down if chased by a creature. Also on each maze there are items that can be collected which allows you to fire a ball at the creatures to stun them but this is limited, and a teleporter that transports you back to your original start position. Once you have filled in the whole maze then you must find a cloud which will take you to the next level. Each level has to be completed within a time limit and the joystick is used to control your hero.