Valkyria Chronicles 2 is the sequel of the same name that was released on PS3. It is a strategy Game.
It is developed and published by Sega. If you are interested, a FAQ is available here. This game exclusive to the PSP also has an ad-hoc mode, which will highlight the cooperative and versus, without elaborating.
Recall also that a demo is available since yesterday on the Japanese Playstation Store.
A new in-game video is therefore to be unveiled for us to wait until its release (January 21, 2010 for Japan and Summer 2010 for Europe and America).