letting go of a piece is sometimes difficult and if a piece is underneath a piece already placed it is possible to pick up the wrong piece - annoying if the piece picked up was in the right place. Also the pieces do not lock together and are not fixed when in the right location.
if the glycolipid reaches either the extreme left or extreme right then it will not move back toward the centre of the screen.
Also it would be nice to be able to stay up in the air a bit longer.
If this happens press ESC and Respawn.