I picked this up as part of a Humble Monthly awhile back and is well worth playing. It is a survival title of sorts, with an isometric perspective and stylized art style; its music is particularly noteworthy and fits the theme very well with lots of harmonica and banjo in melodious, often relaxing tones as you float down the river. Made by team members from Bioshock and other titles, it takes place in a post-apocalyptic world where there is great flooding and devastation. There is both a story-based campaign and an "endless/sandbox" type mode. Players must raft their way down a rushing river, foraging for supplies when they disembark, fighting off wild animals and other threats along the way. Build and craft to keep up your various stats, upgrade your raft, and defend yourself. Learn more about the world and take various quests for reward and lore flavor, especially in the campaign mode which has an overarching story.
Normally the game is $15 so this is a nice bargain on a solid indie title. Support for WIndows and Mac are present but sadly no Linux, though I hear it runs well in WINE and I'll have to test it myself.