This episode is the best in ten years, if not the best ever. In order to appreciate the humor in it, you need to understand a few things about World of Warcraft and also to have seen the South Park episodes in which South Park parodied The Simpsons and World of Warcraft.
Let's start with a brief overview of the South Park episode which was titled (I think) "The Simpsons Already Did It."
In that SP episode, a character is earnestly trying to become a world-class super-villain. He hatches a plot to build a shield to block the sunlight from reaching South Park. When he explains this idea to his sidekick, the sidekick agrees that it will be cool, just like the time it happened on "The Simpsons" (which is true.)
Our would-be super-villain is visibly deflated over the fact that his idea isn't original, so he abandons that idea and after considerable cogitation, thinks up another nefarious plot to wreak vengeance on the residents of South Park (SP). He excitedly explains the plot to his sidekick and once again is crushed to find out that his idea had already been implemented on "The Simpsons." This repeats dozens of times until he just gives up.
There's a reasonably good chance that the plot of that SP episode was inspired by the real-life frustrations of the SP writers, because "The Simpsons" has used up a lot of good gags which otherwise might have been thought up and used by Matt and Trey (the creators and writers of SP.)
Later, South Park did an episode parodying World of Warcraft, which I will refer to as WoW. That SP episode was terrific, and I beg you to understand that the following is not a criticism of the episode but an explanation of something I'll get to later.
There were two major differences in the SP parody of WoW and the game itself. First, when the characters in SP were being shown playing the game, they were talking with each other--not an ability the game has in itself but something you can rig up--but when they spoke, their characters' mouths moved and they gesticulated exactly as though they were carrying on a conversation in real life. This can't happen in WoW. Your character will gesticulate with certain commands, but doesn't have any way to any voice communication whatsoever.
Second, the plot of the episode was that a single character had gotten so powerful, he was able to kill all the other characters in the game, making all the other players miserable because as soon as they started having fun the powerful one would kill their character. This is impossible, the game is set up so that can't happen. The highest you can get is level 60 (or level 70 with the expansion pack) and there are plenty of other level 70 players around who are as powerful as you. At that point if you battle another character, the contest is determined by player skill, including strategy and reflexes, and to a slight degree by luck (some classes of characters have advantages over others, though the game manufacturer tries to keep them as balanced as possible.) So the whole plot of the parodical episode of SP was based on a blatantly false premise. (If you are a low-level player, high-level players can kill you if they are the opposite faction, but only in certain areas--and there's no reason for low-level players to venture into those areas.)
Once again, I am NOT pointing these things out as flaws in the SP episode, I consider them "artistic license" in order to make the episode more interesting. But they were, in the strictest possible sense, inaccuracies, since South Park chose World of Warcraft *by name* rather than using a parodical name.
Now, this brings us to "Marge Gamer."
Though the game parodied in "The Simpsons" was referred to as Earthland Realms and had similarities to many online role-playing games, it had a number of elements unique enough to WoW to leave no doubt as to the target of the parody.
As soon as the game starts (after the introductory sequence and tutorial) we see characters speaking aloud and gesticulating in coordination, exactly as South Park showed it. At first, I assumed this was either sloppiness on the part of the writers, or that they were copying what they had seen on the SP episode out of sheer laziness and lack of originality but later I realized differently. It turned out that the plot of the Earthland Realms story was essentially identical to the plot of the South Park episode: one player ruins the game for all the other players because he's so powerful none can stand against him.
DING!
The light switched on, the slider made it to the top of the pole and struck the bell. This Simpsons episode was not only parodying WoW, it was also parodying SP by point out that SP can take ideas that The Simpsons writers could have used--by using the same idea, *in *the *exact *same *way! This blatant rip-off of that SP episode (right down to the inaccuracies) was IMO a brilliant way to parody not only the Simpsons parody of South Park but the WoW episode at the same time.
Moreover, "The Simpsons" made this just a part of a larger plot--it turned out one of the players getting harassed was played by Marge, and the ultra-high level bully turned out to be Bart. It worked out that Bart and Marge shared a mother-son bonding experience that had a small amount of actual human drama to it, which I saw as a way in which Simpsons writers thumbed their noses at SP--by demonstrating that their show isn't just gags and parody but is more because it has another whole dimension that SP lacks. I'm not saying I agree with this judgment, just that it seemed like a point that the writers were trying to make.
Bravo, Simpsons writers! I'd like to see Matt and Trey top that!