Rain World is a game that's the work of two people, Joar Jakobsson and James Primate. They've spent two years building a world where rain is deadly, monsters will kill you and you control a slugcat that's a lot cuter than anything with the word "slug" in its name has any right to be.
It's due at the end of 2014 on both PC and Mac. You can check out more - and contribute to the game's Kickstarter - below.
Rain World [Kickstarter]