If you want to buy Darkest Dungeon, there are many places to do that including Steam and the Humble store, but through the Windows Store is NOT one of them. According to the developer of the game, someone has put a listing for the game up on the Windows Store and it is a very obvious scam.
The scammer, Balaji Chowdary, even uploaded an image from the game using a non-activated copy of Windows (see top image)!...

If you want to buy Darkest Dungeon, there are many places to do that including Steam and the Humble store, but through the Windows Store is NO...