Q Billion is a puzzle game rated E for the GameBoy by SETA Interactive. In it the player takes control of a mouse as he attempts to make every block read the number one for some reason. It was released in Japan in 1989 and in North America in 1990.
In it you controlled a mouse that, for reasons that are left unclear, has to reduce stacks of blocks to units one block high. This is represented by a grid in which several squares have numbers, representing how many blocks are there. The player can move a single block around, or push a block down off a stack. However, to push a block the player must be standing on a block one level lower than the block - i.e. to push a block off the top of a three-block stack, the player must be standing on a two-block stack.