In Cosmic Chasm, the player's mission is to penetrate an alien planet underground maze and destroy the planet's power structure in the central cavern. It can be played by one or two players taking turns. The maze consists of several caverns connected by tunnels. The player is shown an overview map before entering each cavern. They have to choose the shortest route towards the centre. Each cavern contains several drones that should be destroyed. Exits to caverns deeper in the system are blocked and must be opened with a drill first. In the middle of each cavern is a trap that slowly expands, the player must avoid touching it at all costs. The further the player penetrates into the system, the faster the drones are moving. After placing the bomb in the centre cavern, the player has 15 seconds to escape the maze, preferably using the way they came in. The game uses three buttons: one for thrust, one for a shield to defend against the drones and one for firing. Points are awarded for destroying the central structure, successfully escaping and drilling through walls.