Imagine have produced a program which is, by today's standards, short of graphics and character, though one which is still quite fun to play.
Jack is stuck at the bottom of the scren and must jump onto the revolving platforms above him. He can only do this when there is a gap in the platform directly above him. There are twenty levels of platform which are harder to negotiate as you get higher. If you fall through a gap in the platform on which you are standing, you go down a level and get knocked out for a few seconds. If you are unlucky you may find yourself falling down a number of levels and unable to do anything about it. A life is only lost if you fall down to the lowest level.
Though the graphics and extent of the game are rather limited it is fairly addictive and fun to play.