You play the part of Trogg the caveman. Climb the ladders and jump across platforms to collect gems for points and light bulbs for extra time before the lights go out.
All the keys must be collected to finish the level and can often only be collected in the right sequence.
Each level is about three screens wide and scrolls as you move across it (The Electron version does not scroll but flips screens).
To hinder Troggs progress, there are statues placed in the way across the level which must be removed by firing a yoyo (Troggs only weapon) at them.
There are also balloons which rise from the bottom and daggers which fly diagonally downwards from the top.