On the planet Rydthar, the inhabitants call themselves Earthlings and they have been forced to leave the planet and settle on the third moon, Xydrahpur. The Earthlings had built Absolute Control Stations (ACS) and placed them all over the planet but they have gone out of control taking over the planet. On their new home it is soon discovered that there is an active ACS deep in the caverns under the surface. A hero is needed to go down through the tunnels and deactivate the ACS and you play one such hero, Starman Jones. Caverns of Xydrahpur is a side view flick-screen game where you control Jones on his spacebike and move through the tunnels of the caverns to locate the ACS. On each screen there is an obstacle like an alien or gates that open and shut which need avoiding. If you touch an obstacle or the cavern walls then you lose one of five lives but you start on the last screen you were on.