What would like to play?

It's a fantasy system though there's no reason you can't convert it. Most people run it using the elder Amberites from the Amber novels but I prefer not to. For example, you could run Ragnarok from Norse Mythology using similar elders of power such as Oberon being Odin; after all Ragnarok ends with all the well known Gods dead and two (?) lesser gods starting over.

What makes it work with PbP is that you can describe your whole fight in advance, style, tricks to use, things you want to try, and the GM can spin it out without going back and forth in multiple posts. Plus, like most rules light systems, it encourages role playing and story telling.

If I run something, it will start in the summer when I have more time to figure out the actual mechanics of how to set up a game on a site as I am not terribly technologically competent.