Hard!  Challenging!  Makes your brain work!  Something you pick up and put down and pick up again!  I don't know much about programming, or at least I didn't before I started this game, I've picked up a surprising amount just figuring out how to solve the puzzles.  My dad and I like to sit down and solve some of the puzzles together, we'll sit for hours passing the keyboard back and forth.  It's so good, I've never played a game like this before- and I've played a lot of puzzle games.  Breaking the rules is fun >:)  

I also really enjoy the level creation feature!  We haven't beaten the actual game entirely, yet, but making our own levels is super fun too!  This is worth its price three times over, I would recommend it to anyone who likes to sit down and think things through and is willing to mess around until they can find an answer- while realizing some levels can and will take days to solve.