The first PSP God of War title, Chains of Olympus, developed primarily by Ready At Dawn along with Santa Monica peering over its shoulders. The game looks to be one of the first truly major releases for PSP.
The primary message Sony is trying to get across for the game is that it's going to be just as epic a game on PSP as it has been on PS2. The developers aren't focused on a secondary character or a simplified concept because it's a portable game.
Rather than present the game as a prequel or a bridge between God of War 1 and 2, the developers have latched on to a specific part of Kratos' timeline to tell the story this time out. Specifically, the 10 years in which Kratos wasn't fighting against the Gods so much as fighting for them.