The Flame in the Flood. "It's an independent production that sends you on an adventure trip. You and your four-legged friend. The game looks a bit like a modern adaptation of the classic "The Oregon Trail". In any case, the free game over the extended weekend just suits you.
The Flame in the Flood 48 Hours Free
You have the next 48 hours (countdown running), the Game "shopping" in the Humble Store. Just log in to Humble Bundle, put the game in the cart and "buy" it. You will then receive a Steam Key that you only need to activate on Valve's gaming platform.