So this is a review of the game based off of trying it for about 20 minutes. Sort of giving you an idea of how it plays and stuff. Well the game runs pretty great with the default settings. I didn't even have to change the mouse sensitivity. The camera speed is perfect. I can actually play this game without getting sick. It's one of the reasons why I don't FPS games much. This game really rocks with multi-player. The two modes depend on what map you play. The Northway map is survival mode where you kill wave after wave of zombies. The game downloads pretty fast. I got it to download in about 20 minutes. Takes about 30 seconds to load up a map. When it's done loading up a map, you click on the bottom right text (which is barely noticeable) to start playing. Once in the map you get about 45 seconds before the game starts. After that it seems like the map restarts and off you go.
If you like free to play games and FPS style games, give it a try.