All gods are available, even chronos- but they cannot have unlimited powers. They are attached to humans, remember, and they are based on the god, they are not the god themselves. 

I make a point to not have a "god" or satan" mask because that's subjective and I don't want a flame war. Chronos is defeat-able in story so i suppose he's okay

I mean, i have the fallen angel lucifer designed in my Deviantart gallery, so almost anything goes.