There have been five God of War games. In each one, Kratos slaughters his way through significant portions of the Greco-Roman pantheon. Wow, you might say, is there anybody left for the Ghost of Sparta to be mad at? Yeah, there is.
In a post on the PlayStation Blog, God of Ascension lead combat designer Jason McDonald and lead game designer Mark Simon say that the Sony Santa Monica team has plenty of material to work with:
Every game is a challenge, but the Greek mythos is so wide and varied. We could never do every myth that it has for us. We don't find it limiting; it's more exciting to explore more areas of it — new gods, new titans, new locales.
Take the Furies. They're primordial. They're from before the gods — they're more powerful than the gods. Some of their abilities are just ridiculous — so powerful. They make really great nemeses for Kratos.
Of course, anybody familiar with Greek mythology at all knows that there are hundreds of Olympians, demigods and spirits in various tales and stories. However, what you don't want with a series like this -- one with no end in sight -- is to have a main character going out and bullying dryads and water nymphs because he's angry all the time. Ascension is a prequel, sure, but eventually a sequel with Kratos will need to figure out if there's energy left in the same ol' mythology.