It occurs to me, on occasion, that Zoroastrianism contains awesome ideas to mine for a campaign world.
I'm certain I'm not the first one to have this idea. I think Dungeons & Zombies had a setting that borrowed from some of this stuff.
My next D&Desque game might have some Zoroastrian flavor, methinks.
Daevas, Towers of Silence*, that kind of thing.
*Yes, I know that's not their true and proper name, but dammit it sounds cool.