If there's one thing you can count on from a successful game series, it's that it will eventually start to go stale. At this point game companies have a choice: keep churning out the same thing every couple of year 'til sales dwindle so badly that there's no point carrying on, or re-invent the series, taking it in a bold new direction. Sometimes this second option breathes new life into a series, perhaps even taking it to even greater heights of success than ever. But there is a big risk of royally screwing it up and making long-time fans feel betrayed and heartbroken. Here are five such 'traitors', named and shamed by Play.