So, apparently posts about Carcosa garner lots of attention, whether truly merited by their content or not. Here's a list of ways that I'll be cherry-picking from Carcosa to enrich my own campaign that I hope has more merit for attention than my last Carcosa post.
1. Psionics: Carcosa has a psionics system that could easily fit on one sheet of a legal pad. I'm going to give it a shot; I've never even seen psionics used in any game I've played in, so this will be a new experience. It should be interesting.
2. Mindflayers: Now that I have a psionics system that is easy and fun to work with, I can introduce mindflayers into my game setting. Anyone have suggestions of reading material I should use for inspiration (that is easily accessible)? The only thing I really have is a Type III (not III.V) Monster Manual. Any help on this would be appreciated.
3. A good foundation for a Barbarian class that is built around immunity to mechanics taking over your character instead of being built around mechanics taking over your character. I'll post a Barbarian class here when I figure the rest of the class out.
4. Really nasty NPCs: I've decided that Carcosan sorcerers in my setting will also be Magic Users. Why are they summoning nasty Old Ones? I've decided that, along with the standard reasons sorcerers summon Old Ones, many sorcerers are trying to destroy dragons, which are inspired by Pellatarum.
5. Endless motive for kidnapping: Strip the colors (or replace them with more standard D&D races), rape and details from the rituals in Carcosa and you have generic PG-13 rituals with a certain number of a certain kind of victims that can be transplanted into any setting. Have a strange number of members of one particular demographic recently disappeared? Before long, my players may immediately go into "sorcerer hunting mode" when they hear that.
6. Ray Guns: Carcosa has a great advanced technological weapons generator that is intended for Space Alien weaponry, but it works just as well for generating lost weapons from before the fall of ancient advanced civilization. D&D is, after all, post-apocalyptic.
7. Nasty Cthuloid entities: Pretty self-explanitory. I should point out that there's a very good set of 13 charts for generating more if ever I "use up" the ones that are included.
8. Making alignment mean something: When Cthuloid entities, Mindflayers (made possible by Carcosa), Shrooms and Dragons (those last two not from Carcosa at all), etc. exercise such control over the setting, Law and Chaos become not just ways of interpreting meaning, but two very different ways for humans and demi-humans to attempt to gain and keep independence. That means that alignment will, for the first time in my game, have concrete courses of action tied to them. (Yes, I realize that what I've described isn't the Carcosan alignment system, where Chaos means allegiance to the Old Ones; the Law-Chaos alignment spectrum I've described comes from thinking about the implications of cherry-picking elements of Carcosa and adding them to my game.)
9. The five lotuses: Each one, in powdered form, has drastic and dangerous effects on those who consume them. One creates non-undead zombies, so that's pretty cool.
10: Three new colors with which to freak my players out: I realize that Geoffrey didn't invent these, but how much on this list did he really invent? The great thing about Carcosa isn't so much that Geoffrey created a setting out of whole cloth but that he synthesized lots of ideas from Appendix N and other traditional D&D sources and then distilled them into fun, easy-to-adjudicate systems and a setting with its own very flavorful atmosphere.
Disclaimer: This is a quasi-review, so, consistent with my policy, I'll point out here that Geoffrey commented on my last post about Carcosa. I haven't had any contact with him other than that.