Depends entirely on how good you are. Some of the later puzzles ranged from 5 minutes getting it on my first run, to basically a pure hour of hell trying everything I could think of. It'll vary a lot person to person.
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I played it for about 31 hours, with maybe 25 hours or so going towards finishing all of the puzzles (some of the last few puzzles took me upwards of half an hour to complete), and the rest being just messing around with the puzzle creator and whatnot.
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