Scattered about a maze of tunnels are flashing crystals, each of which is worth ten points, but you have only a limited time to reach them before your oxygen supply runs out. Beware too of the evil guardian who can glide through the tunnel walls and destroy you on contact.

If you manage to reach the top of the maze, you earn 100 bonus points. Control keys are A and Z to move up and down, and left and right arrowed cursor keys.

Tunnel Trouble was written for the BBC B by Simon Rear of Immingham, South Humberside.