This was a movie about the Spartans, not Xerxes vrs. Greece. Part two may be about the Battle of Marathon, and there would probably be a few interesting scenes with the Athenians if they focused on what the Spartans called 'boy lovers and philosophers' in the beginning of 300. (I DID see the movie only once, but I have a good memory). Ships versus Kraken or sea monsters or whatever on Xerxes' side, perhaps. The Battle of Marathon. Things like that.