"What is the most resilient parasite? An idea. Resilient, highly contagious. Once an idea has taken hold of the brain it's almost impossible to eradicate..."
The Junkyard: This is the place where I'll post campaign ideas, notions, and high concepts that just haven't gotten built. Yet.
My love for the GAZ3, Principalities of Glantri, is disproportionate to the amount of time it's actually seen use on the game table, but it's a perennial visitor during my bouts of Gamer ADD when I'm casting around for a new campaign setting. One of these days.
Glantri did magic-as-technology long before Eberron; it did the Great School of Magic well before Hogwarts (and had arcaners vs mundaners); it's had vampire, lich and werewolf wizards in various dark brotherhoods well before the Camarilla and WOD; it's got power politics, skullduggery, and even a few cameos from Clark Ashton Smith's Averoigne (courtesy of X2 Castle Amber). Glantri City is riddled with twisting canals and waterways like Venice, and the streets are home to conniving cabals of every sort, including powerful thieves and assassin's guilds. There's quite a bit of tongue-in-cheek humor, too, so the tone can be adjusted lighter or darker to fit your own vision - it wouldn't be hard to run a Glantri-game like Discworld, for instance.
The Glantri sourcebook has quite a bit of rules-crunch - there are skill bolt-ons to the magic user class to allow things like potion making, elemental mastery, dracology, to necromancy; there are alternate XP rules for magic research, alternate rules for spell and item creation, and a new Path to Immortality by mastering Glantri's unique magical source, the Radiance. The later editions of Classic D&D - BECMI and the Rules Cyclopedia - went from levels 1-36 and had an end-game focused on gaining immortality.
I've often thought if I wanted to run a campaign with byzantine politics, backstabbing, and "Tales of the Dying Earth" style roguery and repartee, I'd place it in Glantri. A megadungeon would provide a good balance of consistent dungeon adventuring versus treacherous politics, and there would be no shortage of patron-wizards to set objectives in the dungeon.
The biggest reason I haven't built a campaign around Glantri yet is "The Mystara effect". I have a love-hate relationship with the Known World (Mystara); it's an odd patchwork of faux-historical nations stuck together, and I'm never sure if I want to set a game there or transplant a Gazetteer somewhere else. When I've done Known World games in the past, they've always been centered around Karameikos and using various classic modules placed in the Grand Duchy.
Stonehell Dungeon: Down Night-Haunted Halls or Castle of the Mad Archmage, two recent OSR products, would be excellent megadungeon center pieces for a Glantri game. And the wheels start to turn in Beedo's mind again...