Huh, I guess I accidentaly answered this on tenth day:
At the moment I consider Goodman Games' take on Dying Earth and Lankhmar to be the best pieces of tie-in fiction. From insane production qualities to great care and love put into the publications, there is little reason not to pick them up—especially when on sale!
My favourite Necromancer Games mega-dungeon—because it is so much more! You get a starting city (with seven adventures), a wilderness area (with 26 keyed encounters and mini adventures), and a mega-dungeon with interesting factions and cool big-bad. Suitable for low-level parties.
Although I'm very, very partial to Dungeons & Dragons Rules Cyclopedia, lately I've been finding the call of the original Dungeons & Dragons rules too difficult to resist. Yes, it is a product of times, but that only makes it more attractive to me. There is everythign there to have an incredibly rich game, without the bloat of latter editions (looking at you 2e!).
Of more modern renditions, or rather retro-clones, I find Swords & Wizardry Complete and Adventurer Conqueror King System to be great, complementary games. The former as front-end, i.e. what the players see, and the former as back-end, i.e. what the Judge uses to flesh out the world, clarify the rulings, run economy, and so on.
Oh my, what a question. I wish I owned original copies of all Judges Guild releases, everything from first and second edition of Middle Earth Role Playing game by Iron Crown Enterprises, everything Glorantha & early Runequest related from Chaosium, everything from a horde of nano-publishers from 70s, 80s, and 90s who did just a few things fro D&D and TTRPGs and then just perished...
I already told you how Rarder Brete died surrounded by hobgoblins, cultists, and other abominations. Now I'll spotlight few character deaths from the Wilderlands campaign I'm running: