Twin-stick shooter with RPG elements containing a very nice crafting system and 3 characters with partially different skill-trees. Besides fighting a decent variety of zombies, you hunt, eat, drink and sleep. Story offers a linear, yet somewhat addicting experience which, by choosing to explore everything, lasts for hours!
There's also Challenge mode and you can play both in Co-Op (online story comes in a month though). Overall graphics and sounds are solid. Except for the main NPC, voice acting and story are lower quality. If you play solo, you may struggle with inventory management a bit, as you're limited to 25 slots (add it to a survival aspect, I guess), thankfully game will save everything you drop. In Co-Op, that's not an issue and you also get to kill your friend.
A very worthy addition to anyone's Steam library.