This is a GREAT game.  The puzzles are really cool (though a few are a little but unlikely and obscure, but still).  This may sound a little strange, but I think what really helps "make" the game is the soundtrack.  The music for this game is PERFECT.  It's so haunting and mysterious.  You just know that there are great mysteries to be unveiled (alright, that sounded really cheesy).  Seriously though, this is awesome.  It's also cool how the game can have a lot of different outcomes depending on what you accomplish and how you do it.