I was suprised at how much fun I was having in this game. Its more co-op and less competitive than the trap-setting survival sprint that is L4D1 & 2. Even though its technically just a wave based survival game, something about the maps and the tension of only being to move so fast, and the great feel of the guns just makes me dig this game. I got it for free on Steam as one of the gifts I got instead of coal. Here's a video of me demonstrating the game mechanics to a skeptic friend.