Well, within the context of strategy games where you can alter the course of history, accuracy largely boils down to accuracy of starting conditions and the logic with which you can alter history. Obviously, a game that perfectly re-creates its starting point at 1066 but lets you quickly develop lasers is not historically accurate (though it may be entertaining!). I wouldn't dismiss EU or TW as "mickey mouse" simply because you can change history in an hour. There's not much point to playing a strategy game when you are limited to the exact outcomes of history.