Like so many other puzzle games of the time, this game involves tiles of different colours, which must be manipulated to clear a succession of increasingly-difficult levels. The basic idea is that you are presented with 2 sets of tiles, and must make the left one identical to the 'control' set on the right. The colours are defined in a sequence - red, green, blue, purple, yellow - and when you click on a tile, that tile's colour moves forward by two in that sequence (for example a blue one becomes yellow), whereas the tiles next to it move by one colour (for example, blue becomes purple). Any that move past the end of the sequence disappear, causing surrounding blocks to drop. You get a limited number of moves, and limited time as well. Fortunately there are passwords, delivered by cutely-drawn naked Japanese girls (although the private parts are covered up).