I don't like that many of the levels are less about creative thinking and more about insanely quick hand-eye coordination. This is supposed to be a puzzle game, not a competition of who can click fastest.
Amazing game, very simple in its mechanics and the increase in level difficulty is good. For me personally, level 50 took as long as all the previous levels combined and I hurt my wrist pressing on the spacebar too hard. 5/5, take a break if you can't do something!
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