i'm semi interested but here's the problem I see. It's a battle of the gods so the whole no god modding is kind of a contraindication. Perhaps add some sort of limitation to the gods/titans. Perhaps while on Earth in mortal form they are limited in strength. Great yes, but not godly. Or like ancient Greeks once did, sects would favor one god over the others so with that you could have armies under the gods. Perhaps the best thing is to mix it up, some gods may focus on a battle of their human subjects while others focus on their own strength. Others try to balance the two. If you decide to do the mix I say in the character sheet you pull a black ops 2 move. People have ten points to spend on their character. If you want your army to have better armor, one point. If you want Poseidon's tritant than that's another and so on.
Up to you though. It's not too far a stretch from the movie if you recall the badguy built up an army of crazy tribal people and attacked those that worshiped the gods.