Puzzles are good though the dying and restarting would be extremely tedious without save states.

Though the endless overly cheery level tune begs you to mute the game and put on some other music, in terms of gameplay this is such a clever, seemingly simple but deceptively complex little puzzle game of geometry and logic and cause and effect, packing enormous amounts of genuinely brain-scratching puzzlework in one screen at a time. Playing through some of the later levels without a guide took me a REALLY long time, but was so worth the satisfaction when I finally grabbed that gem.