Some people consider the GM to be the equivalent of the Creator (however you term him, her or it.) I'm not sure if that is a good metaphor. The Creator, I'm told, doesn't roll dice. But then diceless rp never grabbed me.
Why should the GM have all the fun (yeah right) of playing a deity? Let your players pick a deity to play. give them some followers and step back! This is particularly fun with build your own stat systems like Risus with it's cliches or any of the FUDGE games. Though I guess with a little work you could make it work for Open d6 or Microlite20.
If you're playing Risus it's easy enough. Give a character a cliche like God of War (5). If you're going to use the same 4-3-2-1 dice scheme or at least 10 dice per character remember to set the task numbers accordingly: the nearly impossible should be about a 10 for your average god (3d is a professional god at minimum, demigods might be a 1 or 2.) So 10 is a good number for various blessings, catastrophes and such. Obviously a Love Goddess would have lower TNs to make someone fall in love than a War God etc. The Sea God would have lower numbers to cause storms etc. A god out of his element might be considered not to have tools of the trade and have some cliches halved or even deemed inappropriate. No one screws with the Death God in the Underworld or the Sky God in a thunder storm.
Now let's invert a trope. Instead of the players being mortal heroes or villains, they are gods. Instead of the GM running the universe at large he runs a party of mortals! Yes the very fools or tools of fate that can derail the cunning plans of the Evil God! Don't tell me you don't have a player like that in your group. We all do. I was mine. The players will concoct their schemes, find the npc hero they favor etc or hate and figure out blessings and curses to fling at them. The Evil God and the GM will work up the monsters to oppose the heroes.
How much can the gods help or hinder the heroes? That's between them. They might act indirectly by teaming up with the heroes unseen. They might appear occasionally in different guises to advise the heroes. Or they might go for the big giant floating head once in the while. The players should get together and draw up an agreement before the game about what divine magics may be tolerated. Anything that breaks the agreement will lead to ... a war of the gods which no one will win.
Besides making things interesting for the GM's heroes the gods may have other things to deal with like the sinking of Atlantis, uprisings or the sacking of their favorite temple. The GM will have to work out whether destruction of temples and followers will actually hurt a god. Maybe humans are like pets. They love us, are often nurturing, condescending, and without a clue what really makes us tick. Killing followers doesn't hurt them physically but it pisses them off.
A GM might be faced with a world wide disaster brought on by deities that are into power gaming. Don't invest a huge amount of detail in your world. It's also possible to have the players start new playing mortal survivors after the world dies and gets better.