Alignment as theme
I’ve been thinking about alignment as a thematic dichotomy. Each campaign could have its own thematic alignment scheme. OD&D is Lawful/Chaotic. Other possibilities might be Civilized/Barbarous (Conan), Mundane/Fey (Strange & Norrell), or New Religion/Old Religion (Arthur). Carcosa is interesting in that it repurposes OD&D’s general Lawful/Chaotic alignment scheme by making it a specific, thematic element of the game: lawful characters oppose releasing Lovecraftian Old Ones from imprisonment, while chaotic characters seek to aid and serve the Great Old Ones.