“ War of the Roses as a campaign plot. Two noble lines converge somehow, each line thinks it has the rightful claim to the throne. Deciding this long ago was handled by some divine intervention, requiring both houses to come together at some point. They aren't so willing to get together this time. Civil war, or a new king?”
“ There is a land where every person wears spectacles. Those without eyeglasses are considered to be the lowest stratum of society, so adventurers without glasses are treated like outcastes. It certainly would explain those heroes wearing sunglasses for no apparent reason...”
“ Pick up a pathology/microbiology book, and add the diseases/syndroms to your game. Your players will freak out.
Coughed at? Diphteria. or tuberculosis?
Drunk from a muddy stream? Or just walked through? Well, let us introduce you to schistosomiasis...
Hit by a stream of energy? Too moch mana is ust like too much radioactivity - perhaps all mages could develop cancer early if too powerful...”