http://www.gamesradar.com/zombie-panic/articles/Valves announcement that theyre working on zombie game Left 4 Dead might have grabbed the headlines, but its the industrious Half-Life 2 and Source engine modding community who are getting the most mileage out of remixing-the-zombie concept. Perhaps a dozen zombie-based mods are currently in...http://www.gamesradar.com/shambling-in-your-direction/Feb. 20, 2007, 7:46 p.m.