As someone who started gaming during 2E, well after Greyhawk heyday, I'd appreciate if a kind soul were to tell why it is such a well-regarded setting. I know the basics, sure, I've read about it online, but I've never really understood what makes the setting tick, what is it that engenders such fan loyalty for what is ultimately a fairly generic sword and sorcery setting? This question isn't meant to be taken confrontationally, but as a sincere query on my part.
Greyhawk is where the roots of the game can be found.
It's hard to explain why people like myself feel so strongly about it. I think part of it was the experience of coming to know the setting, and loving the way you slowly learned many of its secrets. For many of us, names and places that are commonly heard in D&D are practically synonymous with Greyhawk. Names like Mordenkainen, Bigby, Tenser, Rary, Robilar, Serten, Nystul, Pelor, Acererak, Vecna, Iuz, Tharizdun, Elemental Evil, Lolth, Drow, Keraptis, Iggwilv, Heironeous, Murlynd, Heward, Nerull, Zagyg etc. The list could really just go on and on and on. For Greyhawk fans, the game itself is often inseparable from this old, beleaguered campaign setting.
The fans have also been put through a very volatile history due to petty disputes and rifts in the company over the years. This is something for which Forgotten Realms fans have rarely suffered. Perhaps the poorly conceived Spell Plague is the only real upheaval they needed to endure. I appreciate the Realms and why it has its fan base , though I have no interest in running my game therein. I take great pride in the fact that the hundreds and hundreds of D&D games I've run over the past 30+ years have all been a part of an ongoing campaign set in the World of Greyhawk. At this point I have mountains of details packed into file cabinets and folders. Copious notes on the well over 100 characters that have trodden through the most classic adventurers ever produced by TSR/WotC, and a large number of my own adventures.
Furthermore, most Greyhawk fans have a sense of melancholy about where their beloved setting may have gone if various events had played out differently from the copyright holders. Some of us still yet have some hope that a brighter future lies ahead for a gorgeous, thick, hardcover filled with maps and details about Oerth.
We all realize that many of the hardcore fans of the Realms, Dark Sun, Dragonlance, and the rest don't care overmuch about Greyhawk. But there's plenty of room for everyone, and it looks like Greyhawk might finally get its long overdo full treatment.
Adventures are another part of what make Greyhawk so special. The bulk of the most famous adventures of all time have all been set there. The Temple of Elemental Evil, Scourge of the Slavelords, Queen of Spiders, White Plume Mountain, Tomb of Horrors, Lost Caverns of Tsojcanth, Expedition to the Barrier Peaks, and a host of other classics. If you are the type of person who remembers looking for Hex 113/K5 to determine where the village of Orlane was located, than you and I speak the same language.
Seeing that worn Greyhawk folio sitting on the edge of Perkins' desk has made this grizzled old 'Hawker very happy indeed.