AD&D Carcosa Crawl - House Rules and Lore Ideas

I've become totally infatuated with Lost Carcosa by Tristan Tanner of the blog The Bogeyman's Cave, to the point that I prefer it overall to Geoffrey McKinney's Carcosa. I think it's only natural to compare the two, given the overlapping subject matter.

That said, I still really enjoy McKinney's Carcosa setting on its own merits, and I have a couple of old ideas for it which I haven't posted about yet. I figure I should get it out of my system before my attention totally turns to Tanner's take on the concept.

I'll be referring to both the core Carcosa book and the four AD&D hexcrawls published through Lulu.com.

AD&D House Rules

• Classes are restricted to Fighters, Clerics, Magic-Users, Illusionists, Assassins, and Monks. (I could be persuaded to include Thieves as well.) Inspired by this thread at the OD&D Discussion Forum.
• For class purposes, either ignore alignment requirements entirely, or ignore the good/evil aspect of alignment. If choosing the latter, Monks must be Lawful, and Clerics must be either Lawful or Chaotic. Maybe Magic-Users should always be Chaotic? The rest, including Illusionists, could probably choose any alignment.
• If not using the Thief class, consider allowing Fighters to use Thief abilities equivalent to their level (like this) except for reading languages, using magical scrolls, and speaking Thieves' Cant.
• Human PCs only. (Unless borrowing mutants or androids from Gamma World, perhaps? Or aliens from Empire of the Petal Throne?)
• Carcosa's sorcerous rituals can be performed by any class, rather than being restricted to a Sorcerer class. Spellcasting classes have their usual spells as well.
• Remove all aspects of sexual assault and harm to children from the rituals.
• Use the psionics system from Carcosa instead of AD&D. Multiply the chances of a PC having psionic powers by 8 (e.g. someone with 18 INT, 18 WIS, and 18 CHA would have a 96% chance).
• The damage dice for space alien weapons are d12s instead of d8s.
• Space Alien weapons may be used by Fighters, Assassins, and Monks. (Thieves as well, if the class is used.)
• Ignore the weird new "Dice Conventions."
• I'd probably ignore weapon speed factors, weapon vs. armor class adjustment, segments, helmet rules, and all that jazz. I'm on the fence about giving weapons different damage vs. different opponent sizes, as well.
• If I DO try using these rules, I'll probably need assistance from THIS or THIS.
• No training time/costs needed to level up.
• No female strength limits.
• No Read Magic, as usual.
• No spell component tracking. (They can still be present as non-mechanical "flavor" if desired.)
• Consider borrowing material from Gamma World, Metamorphosis Alpha, and Empire of the Petal Throne.

Lore Alterations and Additions

• Carcosa is either Earth in the distant future or a planet colonized by future humanity. At some point between now and the game's era, the human race has mostly split into two distinct new species through mysterious means: the Lawful high-tech Space "Aliens" and the Chaotic sorcerous Snake-Men. The former have mostly abandoned Carcosa, while the latter were destroyed by the "ultratelluric forces" unleashed by the Snake-Men when they summoned (or created?) the interdimensional reality-warping dream-city also known as Carcosa (which may also be a living idea and/or a god).
• "Brown Men" are just normal, unaltered Earthly humans as we know them in our era, the predecessors to the two aforementioned posthuman species. They may have originally arrived on Carcosa via time-travel, or they may have been recreated post-extinction by the Snake-Men from preserved genetic material and eldritch sorcery, or they could have simply continued to survive alongside the Space "Aliens" and Snake-Men all this time while somehow remaining unchanged. In short, they are the remains of "original" humanity. Thus, they have the same variety of skin/hair/eye colors found in real people today, rather than the more uniform features described in the book.
• The other twelve "species" of humans are creations of the Snake-Men, as per the book. All thirteen types of humans were used by the Snake-Men as ingredients in horrible rituals, and the latter twelve types were engineered from the "Brown Men" to enable a wider variety of sorcery than that which could be accomplished through the sacrifices of only one kind of human.
• I'm considering changing the names and appearances of the "Black Men" and "White Men" of the setting, partly to further differentiate Carcosan people from real-life racial or ethnic groups and hopefully prevent any confusion or accidental unfortunate implications, and partly as an excuse to include more super-weird people à la the Bone Men. Maybe they could be Muscle Men and Blood Men?
• A friend pointed out to me that Claytonian JP came up with better names for Carcosa's technicolor peoples in "A Carcosa Hack," found HERE. I definitely prefer the terms "Umber Men" and "Ebon Men" and "Chalk Men" for Carcosan folk over terms that have greater real-life connotations.
• B'yakhee, Deep Ones, Yithians, Mi-Go, Primordial Ones, and Shoggoths are not merely different varieties of spawn produced by "The Black Goat of the Woods with a Thousand Young." Instead, they retain their original Lovecraftian/Cthulhu Mythos origins - or at least their origins as described in the Call of Cthulhu RPG.
• If the new colors of Carcosa need to be visually depicted (for character portraits, miniatures, etc.) here's my shorthand:
• Jale = Cyan
• Ulfire = Magenta
• Dolm = Indigo

Bonus: The Keep on the Borderlands - Magic Item Conversions and Other Suggestions for Carcosa

• Amulet of Protection from Good = Half damage from all mundane attacks rather than protection from "good." Instead of an amulet it's a chemical with which the body was treated, and thus it's not "collectable."
• Amulet of Protection from Turning = Same effect, but instead of an amulet it's a chemical with which the body was treated, and thus it's not "collectable."
• Arrow +1 = Bow w/ 2d10 Arrows coated in Black Lotus Powder
• Dagger +1 = Blowpipe w/ 2d10 Darts coated in Black Lotus Powder
• Elven Boots = Night Vision Goggles w/ d6 Hours of power left
• Elven Cloak = Cloaking Device w/ d4 Hours of power left
• Hand Axe +1 = Hand Axe coated w/ 3d8 doses/hits worth of Black Lotus Powder
• Helm of Alignment Change = 3d10 doses of White Lotus Powder
• Mace +1 = Lightning Bolt Pistol w/ 3d20 shots (Beam)
• Plate Mail +1 = Reflective Armor, reflects 10 "spectral colors" of lasers as one of its electromagnetic resistances
• Ring of Fire Resistance = Space Suit w/ extra thermal protection (same effect as Ring)
• Ring of Protection +1 = Absorption Field w/ 3d10+10 HP, tuned to all colors of lasers ("Full HP" was 50, so it could be charged up to 100 HP)
• Rope of Climbing = Hand-Pumped Pneumatic Steel Cable Grappling Hook Gun.
• Shield +1 = Force Field w/ 3d10+40 HP (Full HP was 100)
• Snake Staff = Grenade Launcher w/ 3d8 Hardening Foam Grenades
• Spear +1 = Spear coated w/ 3d8 doses/hits worth of Black Lotus Powder
• Staff of Healing = Grenade Launcher w/ 3d8 Sonic Grenades
• Sword -1 = Dolm Pudding Emitter Pistol w/ d20 shots (Broken: Stuck on 360° mode, hits user)
• Sword +1 = Laser Pistol w/ 3d20 shots (50/50 chance of Pulse or Beam, random Color)
• Sword +2 = Laser Rifle w/ 3d12 shots (50/50 chance of Pulse or Beam, random Electromagnetic)
• Wand of Enemy Detection = 2d6 Insanity Hand Grenades
• Wand of Paralyzation = 2d4 Paralyzation Hand Grenades
• Potions and Scrolls remain the same.

I would place the adventure in Hex 0605 on the Carcosa Campaign Map #1. The orcs, goblins, kobolds, etc. are all heavily mutated humans transformed by the giant crystals located in this hex. Perhaps the mutation process has also brainwashed them into serving some malign, Chaotic entity of eldritch, ethereal evil; hence the name of the Caves in which the mutants dwell.