I have not been able to stop thinking about this game. Several questions about the setting have come up. I ask them from a place of excitement, which I say because with my tone I probably come off like I'm being a downer.
How does the law treat non-human heroes? For example, someone gets bitten by a radioactive weevil and develops weevil-like powers, so they go to their doctor to find out what's wrong with them. Does the doctor still have a responsibility to protect Weevil-Man's private medical information and not disclose this mutation to a government agency?
How much do you intend to define other races in the setting? Will players be allowed to say they come from a secret subterranean race of creatures? Will you provide a list of aliens and their traits which is permissible for players to choose to base their characters on? How about which mythologies, if any, are true or at least based in fact? Will characters be permitted to help define the setting by creating characters who are part of a pantheon and/or the secret Ancient Aliens who really built Stonehenge or whatever?
What overall tone are you going for? If this game was a movie, what would the MPAA rate it?
If you're using a system that has mechanics to model them rather than a consent-based system like most mixed universe games, do you intend to implement any particular rules or protections against effects that can control another character's mind?