The game will feature a first person perspective with arena-based multiplayer gameplay. The game will also run on the Unreal Engine 3 - which is probably the best engine for a FPS game. This game will mark the first FPS developed solely for the PSN.
Zen Studios have set up an official website for the game and will update it to provide more details as they come. You can visit the site at http://www.punishernomercy.com/