In an open letter to fans, MGS designer Hideo Kojima says that Metal Gear Solid: Peace Walker will be a "full-featured" sequel that will be so full of content it will "require hundreds of hours to complete".
"The main team from MGS4 is participating in the development of this title and I am involved in all aspects of the game, ranging from design, direction and scenario writing," Kojima writes in the latest issue of Konami's internal magazine On Screen, which is being handed out at Gamescom this week.
Peace Walker will be set in the Costa Rica of the 1970s, ten years after the events of Metal Gear Solid 3. The story will have Snake and his crew questioning their purpose as they battle to defend a nation without a military from foreign invasion, Kojima writes.
The developer also says that the game will be a graphically beautiful title.
"Despite being on the PSP, we don't plan on making any compromises with the graphics," he writes. "The art team is used to producing PS3-level quality and the results will make you wonder if this is really a PSP game."
Peace Walker will also include many features unique to the PSP platform, he writes, and a new gameplay system.