I'm on record with my opinion that one need not be an expert on a given setting in order to run a roleplaying game in that setting.
This came up most recently in my gaming circle with respect to The Discworld RPG. A GURPS GM was pontificating on games that might be floated and I suggested Discworld (a GURPS-based game) only to be told that while he loved the setting he didn't feel he could do it justice. He also felt that the players would be highly challenged trying to duplicate Terry Pratchett's humour style.
I reacted strongly (and badly) to this, opining in no uncertain terms that if we were to wait while someone became an expert on what was - when examined in depth - a body of work that had changed with almost every book added to the series and was still changing, well, we'd all be lying in a pine box under six feet or so of soil.
The clear implication was that the idea would be to somehow duplicate Pratchett's style when running the game, but at what point would the game take place? Pratchett's style was not the same in the opening three books as it was by Moving Pictures (something like the tenth in the series) which in turn was not the same as Making Money (well into the twenties or possibly tweaking the thirties - I dunno, I just read 'em I don't count 'em). I felt (and still feel) that this evasion was a never-resolving one, and would result in no game, ever.
I also felt that announcing that should a game run, the players would also need to be experts in the Pratchett style was a monstrously unfair precondition and more to the point not germane. The story we would unfold would be ours, not Rincewind's or Vimes's or ... well, you get
the picture.
And this is the key point I feel that many people miss. The point in playing any setting, be it Middle Earth, Gormenghast, The Disc, Barrayar or the deck of a Federation Star Ship, is not to recapitulate someone else's story in some sort of bizarre tribute RPG, but to have new and therefore unknown and exciting adventures of one's own, be they over the sights of a phaser or whispered campaigns of intrigue in the Court of Elric. Who on earth would want to play that other sort of game?
Note that I don't say the GM must have no "buy-in". I've attempted to run games in which my personal resonance was low, my prior experience not voluminous, or to put it another way, in which my buy-in was zero. They were all-but universally a bad time for all (a notable exception being Space 1889 that turned out to be unexpectedly riveting while prepping for my first game and is now a favourite), at least until I was able to reconcile the parts I found a turn-off with my personal vision of what the game could be. The trick to doing that is to warn everyone what's going on and to stay in touch with the core values of whatever it is you are tweaking. If you don't, you end up in a classic Bait-and-Switch which the players will never forgive you for.
Which is why I cannot for the life of me work out why I volunteered to run All Flesh Must Be Eaten, a game of the Zombie Apocalypse. I like watching zombie movies as much as anyone, but I don't live and breath the milieu and I really think that might be what is required to make this game shine.
However, I've been running Lovecraftian Gothic Horror RPGs since they were invented and have a good feel for how to pace a scenario for the time slot we have (four hours) so I have dredged my rather superficial knowledge of the movies for tropes and think I have a rather neat scenario along with a twist I don't think the players will see coming, and I'm throwing myself into the rulebook so I know how the game should flow.
The only thing I'm not doing is making excuses because I'm not word perfect on the body of Zombie movies out there.
