Save and Quit: "With the release of the Cold Stream Beta on Steam, the PC version of Left 4 Dead 2 has seen a little bit of a revival in terms of player numbers. New content is always bound to bring people back to a game and keep them playing, but when there’s so little spread as thin as it is in L4D2, it’s hard for some of us to stay interested.
An excellent example of just how new content can be used to keep a game fresh and exciting can be found in Valve’s Team Fortress 2. Love or hate the hats and unlockable weapons, they give players ways of changing their game experience and provide goals and rewards for playing outside of achievements. While Team Fortress 2 may be a brilliantly fun first person shooter with a lot of personality, I’m not sure I would still play it as religiously as I do were it not for the promise of new items, crafting, trading, and silly hats."