Dominion

Picture a colony in the far reaches of space, a huge colony hewn out of rock on the populated word known as Lamina. Dominion is set in a series of corridors descending into the planet. At its heart lies a radioactive hell spewing out death-dealing energy to the surface. A construction team is busy trying to build a defense and needs the ore badly. Starting in the top levels of the station you're charged with the task of venturing deeper and deeper into the planet, finding ore for the construction crews.

Unfortunately. a passing alien fleet has decided to enter Lamina's corridors, eager for radiation to power their ships. They do not look happily on attempts to cut-off the radiation. The battle to calm the escape of the radioactive gases is never-ending, but if you reach the 20th rank you'll die the most honored of heroes. After all, who said life was fair? Published in Zzap!64 Megatape #07 that accompanied the Magazine issue 62.