You have to keep the pit free of blocks by moving and rotating the small pieces as they fall from the top of the playfield. Some blocks are partly tranparent, and they have to be combined with other transparent sections. Each time a complete row is filled, it vanishes and all blocks above fall down.
The game is over when the pit is too full for the next piece. The game becomes a bit faster each time 15 rows have been erased.
Mixline features high scores and sound effects.