This game originates from the early days of personal computing. The scenario is very simple: there is ground level and six floors, with several holes which permanently travel left and right. Jack can jump up thru those holes, but also fall down, in which case he will be unconscious for some time. If he falls down to the ground level, he loses one life. He also has to avoid several enemies, coming from left, right and falling above, as each contact with them will cost him one life. One of those figures (boxed rotating heart at the left of the screenshot) will not take but give him one life, and the shield (the big dotted rotating circle, top right on the picture) will n ot only add one more life, but also protect him from all enemies for some time. There is a total of five lives at the beginning.

There are two elevators which will not take him upstairs, but only downstairs. Elevators will automatically come when he approaches it. When he enters the elevator on the upper floor, the light in that elevator will automatically turn on. His goal is to switch the light on in both elevators, and the next level will be started. There is a total of 13 levels, each of them harder that the previous one, as more and more enemies appear. After level 7, some obstacles will also be positioned on some floors.