Now that I'm asking, how easy do you think it is to do your own mythologies? I'd love to get my Maya on the table using this. Are there provisions for doing that?
Yes, as with most of the 'Song Of...' stable of games there's a system for inventing and calculating your own creations. We made a giant 'hero' for this game for instance.
When I played with my son he insisted Poseidon be as powerful as Zeus, so we were able to make that change too.
You have basic stats and then a series of special rules all of which have points cost then there are multipying factors for god's or heroes.
I believe someone on the FB group may already have done Mayan gods.