A small, primitive village has yet to discover fire, which is a good thing because there are highly flammable (but not otherwise dangerous) gasses in the air. The heroes, blissful in their ignorance, don't know that and think it a wonderful idea to show the locals open flame.
Unbeknownest to the character, he is in the royal bllodline. Suddenly the majority of royals fall ill and die, and the hero is left with the crown, but no experience or idea of what to do.
A Deity of some sort has unleashed a plague of bookworms or something like that in the area. Almost all spellbooks are destroyed, along with bardic and historical books.
"The world has an immovable dark red sun in the centre of the sky that produces very little light. The heat is totally unbearable and the aroma of delicious cooking meat is in the air. To look around it appears as though you are surrounded by giant black mountains with no vegetation anywhere. The ground is soft and an oily liquid flows into your footprints. Travelling reveals nothing else."
Any character without some resistance to fire or heat is slowly being cooked. The ground if you haven't guessed it is the cooked meat.
I've wanted this world to be part of a dimensional hopping "chase". I thought maybe to populate this world with giant carnivorous beetles or perhaps this could be a "Nirvana" for deceased or living (but dimension travelling) fire dragons.
Perhaps I've just been grilling a little too much meat or perhaps there are some great ideas out there on how to spruce up the place. Any suggestions?