So you've probably heard every rumor there is to hear about the God of War franchise - especially that God of War 3 isn't the end of the sequential franchise - but I'm here to lay down the spoiler free truth, and the truth only. Forget everything everyone else has told you, these are properly researched facts, and I WILL mention it if I start predictions.
Let me just clear the air about the supposed "God of War 4": Sant Monica mave no intentions at this point to carry on the series sequentially. At the very beginning of God of War, they had it planned strictly as a trilogy, and don't want to upset that balance. That's why they are doing prequels to games - it's the only way to go. Now, Ghost of Sparta is the upcoming PSP God of War title, and is set between God of War 1 + 2, but more precisely, between 1 and GoW: Betrayal, the little-known moblie game. GoW: Betrayal was also set between 1 + 2, but had little effect on the story line. Since this is before betrayal, Kraots could possibly be trying to win over the Gods to prove himself worthy, as he is new to Mount Olympus. Anyway, Ghost of Sparta hasn't had much information released, but here's the run-down of the first trailer, and a video of it. - http://www.youtube.com/watc...
Basically, Gaia narrates about Kratos while he advances towards an island, where he looks into the water and sees his reflection as a young boy. This shows that Ghost of Sparta could have much to to with his past, possibly even including his long-lost "brother" that was mentioned in God of War 1, but never seen.
Now, onto facts of the game, shown by the demo and developer information. That island, as it has been confirmed now, was Atlantis. Kratos is heading there by boat in the middle of a storm, where he is attacked by the Scylla, a sea creature in Greek Mythology. He eventually frives it off in a mini boss fight, and carries on to Atlantis. Kratos then finds himself collecting "The Eye of Atlantis", a magic power-up that works similar to Poseidon's Rage, or Cronos' Rage. After that, he finds a new weapon, that is just a plain shield and sword. He then makes his way through the Atlantian streets, fighting his enemies, until he comes across Garron. He defeats him by crushing him with his own weapon, then the Scylla is seen in the distance, as Kratos speeds off.
Another section of the demo shows Kratos in some underground, volcanic scene, and he is fighting King Midas. As he tries to touch you to turn Kratos to gold, Kratos knocks him unconscious and carries him towards the surrounding lava, and melts him. That is the basic run-down of the demos.
It is widely assumed that Kratos somehow destroys Atlantis, as Poseidon shout in God of War 3, "Atlantis will be AVENGED!!" Also, and this is strange, but it has been said that this will explain the origin of Kraots' tattoo.... Ok......
This is basically all I have to say on the matter... Oh, one more thing: If you have seen a video on Youtube, or any video-sharing site called "God of War IV Trailer", ignore it. it is clearly fanmade, and many people are just soaking it up.
If you have any more questions about Ghost of Sparta or any God of War game, comment and I'll try my best to answer you. Also, what do you think about Ghost of Sparta so far?