This game has been rumored for ages now, but Sony has finally officially announced PlayStation All-Stars Battle Royale. Like Smash Bros for the Nintendo, this game features a collection of Sony characters battling each other in side scrolling action.
Up to four people can play this game and you'll be battling it out in backgrounds that are mash-ups of various games. For example, one of the levels shown has the Patapon folks invading Hades's domain of God of War.
A few characters are shown in the trailer such as the awesome Parappa the Rappa and Fat Princess. Now, no official list of characters were announced so let the speculation begin, but I'm sure they'll be fortified by more after the game via DLC.
Anyways, here's your first official look at All-Stars Battle Royale.