I have now completed the game without any hints or guides. It had plenty of truly brilliant puzzles and fun moments, but I felt that near the end of the game, it devolved into tedium and the puzzles seem to get easier, repeating ideas from puzzle to puzzle. It's also overpriced. Still, the game did provide plenty of good fun, and there were still great, enjoyable puzzles right up to the end. There's some okay music and a plot, too...