Underworld

Underworld is a single player, shareware, variant of the game Dig Dug.

In this game the player controls a miner who is tasked with clearing all unauthorised life from the planet. This means going underground as soon as possible, there's radiation on the surface that will kill very quickly, and zapping them. There are two kinds of monsters, Puff Dragons and DyclopsPoo Poos and all the miner has to fight them with is a grappling pump that fires missiles which inject them with air making them explode.

The Puff Dragons walk around the mines tunnels breathing fire balls which can blast away rock. The Dyclops will turn into ghosts and travel through the rock to attack the player. Any contact with either is fatal and costs the player a life.
As in the original game rocks are scattered throughout the earth and these can be used to squash the monsters.

The game is keyboard controlled by default but also supports joypad and joystick.

The shareware release has thirteen levels while the registered version has thirty one.