But very, very indie. I've spoken with Johnathan Blow, it's lead designer, a couple times; the guy has very high standards for himself, and very much views games as a budding artform. His games are not meant to be fun, but rather to be an artistic experience.

And Braid fits the bill. Very artistic, very interesting interweaving of minimalistic story with game mechanics. Very very cool game mechanics, too: It's divided into "worlds," which each other introducing a major mechanic. In the first world it introduces the time-rewinding - which has no limitations by the way, and can be used infinitely. One of the later worlds is set up so that whenever you walk to the right the time moves forward, and whenever to walk to the left the time moves backwards. Another world is set up so that when you rewind time you leave a shadow version of yourself behind, that then does whatever action you just undid. Stuff like that, and it is very masterfully done.

Whether or not it's worth 15$ really depends on the person; it's definitely not a game for everyone. If you think you can appreciate a slower-paced game about exploring the artistic side of game systems, with lots of pretty art and game references, then it's definitely worth picking up.