I've written quite extensively on the Mongoose Publishing version of the Traveller science-fiction RPG, either clarifying or fixing fuzzy rules, or adding background and flavor for my game.
A D&D/Pathfinder campaign world I am creating which has recurring themes of elementalism, gonzo pseudo-clockwork universes, and older races creating servitor races which rebel against them.The cyclic nature of reality is emphasized and, in some cases, actually measurable.
I explain, in great detail, how the six core characters of My Little Pony: Friendship is Magic comprise a functional Dungeons & Dragons adventuring party.
My version of a My Little Pony: Friendship is Magic RPG, where the characters are all blank-flanks in search of their cutie marks. Uses the Unknown Armies engine.
A superior for the In Nomine RPG.