Seems like Steam or the Developers offer "Stories: The Path of Destinies" free on Steam as well - without the need to do all that screenshooting and sending proof etc.
However, the key from the "Wishlist Quest" will give you the Collector's Bundle which includes Soundtrack and Artbook but I will add the game free on Steam now anyway as then anything that comes out of the thing the developers do with their combined giveaway/competition is a bonus.
Enjoy.
P.S: Add once, game stays permanently in your library.
You just have to initiate the download/install process, not actually finish it, for the game to appear in your library; for those who don't want to install it right now.