The objective is simple: Stop each row by pressing the STOP DRIFT button, so that the blocks are placed directly above the previous row's blocks. As rows get added, your score increases. Make it all the way to the "bonus" zone and you get to continue to the next level.
Sound simple enough? Well it is...but this game will suck you in very quickly as it defeats you just when you think it's easy. It's a great game to play quickly, yet also be drawn back again and again to beat your previous score.