I could write a 50 page novel on why everybody who loves games should play this game, but instead ill just say: GET IT.
So, why is this game so popular? You never, ever kill anything in it...exactly. This game totally defies the traditional aspect of video games in that in order to have fun in interactive entertainment you must be able to eliminate SOMETHING. However, in Journey you do not eliminate anything. You actually create things. Along the way you will find artifacts that seem to be apart of your past and help you along the way. In case the rest of this was tl;dr the only other thing I can say is: buy this game...its only $15 and is far worth the cost/time entertainment ratio. No doubt.
EDIT: I must stress, however, that it is not a puzzle game like Tetris. It is almost something of its own genre. But DEFINITELY not a puzzle game.