Hideo Kojima has said that Metal Gear Solid: Peace Walker's release on PSP is a 'test' to determine which directions Konami can take the franchise in.

Writing on his Twitter account, the MGS head said: "It's difficult to show the interest and freshness of PW through video. Cameron's Avatar was a huge hit because of the 3D video. That can't be communicated through text and a trailer. It's something you won't understand unless you experience it for yourself in the theater."

In a later tweet, he added: "It's not that PSP is the main platform for the future MGS series. PW is a test to see what type of expansions are there if MGS is brought to a portable. We're not just rising vertically with development on next generation systems, but also horizontally, trying to expand gameplay."

Metal Gear Solid: Peace Walker's release date is May 28th, after a delay Kojima branded 'a crime'.