Remember when Half-Life came out in 1998 and it was one of the best first-person shooters ever made? Remember when the same thing happened in 2004 when Half-Life 2 came out? And in 2007 with Half-Life 2: Episode Two? Not too many franchises out there boast such preposterous standards of quality. Few can hope to be as memorable. None have induced such acute anxiety in their fan bases...