I won't be ashamed to admit that I had to look online for help in solving some of the much tougher puzzles and if I did them without help, I felt smarter. (gearnuke.com)
I can't wait to see what new elements later levels hold, and how tough the puzzles become. (thatvideogameblog.com)
There's 80 two cube levels, 40 four cube levels and then you can also unlock the vault, which is a collection of super tough puzzles that show no mercy. (the-gamers-lounge.com)