So, here's a pretty cool idea.
A sort of fantasy DnD setting, right, except the dungeons are a system of underground tunnels from an ancient civilization. Magic comes from the Dragons, who live in the sky. Great machine-treasures lie underground.
And people are dying. There's a great miasma, a poisonous atmosphere, that makes people deteriorate at rapid rates. And monsters live in the miasma.
The good news? The cities and towns have machines that fight off the miasma and defense systems that can attack the monsters.
The bad news? Nobody knows how these machines work. And they eat through power. Quickly.
Your character is an adventurer. You go into the ruins and look for power sources. You arm yourself with half-usable devices because the deeper you go the weaker the magic you relied on topside gets. And you have to move really quickly. Because the power's running out, so you've got to find more. NOW!
So, any ideas? Comments, etc... welcome.