What we're talking about: Ratchet & Clank: All 4 One is the next installment in the Ratchet & Clank series -- now heavily featuring four-player cooperative play.

Where we saw it: At a private appointment Sony set up for journalists at the Grand Hyatt Hotel across from the Convention Center housing PAX.

What you need to know:

• This game is meant to be all about co-op, but can solo it. We're told the game will give you a single A.I. partner to help out, but details on this mode haven't been hammered out by the developer yet.


• Pickups make the co-op play slightly competitive; you're going to want to grab more bolts, get to things first, be the first to finish winding up a gun or shooting a grapple. The only rewards or punishments for being a bad teammate, however, come from stats, not in-game penalties. You can be the player that always falls off of cliffs and the game still respawns you quickly to keep you in the action. Meanhile, there are no actual penalties for griefing your co-op crew and it is hard to resist.


• This is not a spin-off -- it's a main franchise story with full-blown cut scenes and a plot that somehow ties into the Ratchet universe in a way that explains why Dr. Nefarious is (sort of) on your side.


• Weapons are where it's at. We saw a Vacuum 4000 that can throw other players across gaps; an Elasti-shot gun that makes a bar between two players which destroys anything it touches; a Pluser Cannon that each player needs to load themselves into, wind up, and fire; and an adorable Voltergeist that needs to be lifted and shot into certain level objects to open doors or charge up barriers.


• There was an interesting-looking level in a robot factory where the four characters are dropped down a shaft with fans at the bottom. By joining hands, the four players could ride a wind stream up in a sort of reverse-sky-diving exercise that brought them to the boss fight of the level. It was a nice visual break from the fixed angle camera shot used throughout the rest of the level.


• The game is linear, but its scale still inspires exploration. Planet Magnus -- The High Cliffs is a level you can see the whole linear path laid out between the cliffs. But it appears blurry and off in the distance, teasing you with glimpses of the puzzles and enemies you'll have to face when you get to that part of the level (and you have no way of knowing when that will be -- the level was 20 to 30 minutes long).


• The developers drew inspiration for co-op from just about every game that ever featured a co-op mode -- Bomberman, Left 4 Dead, LittleBigPlanet, you name it.


• The camera stays fixed in a director's shot view so that none of the four characters ever goes off screen. This view isn’t used in full cut scenes.

Point in development cycle: Alpha -- they wouldn't let journalists touch it. The game is due out in fall of 2011.

My take: I'm a fan of the Ratchet & Clank series*, and I like co-op games like Bomberman, LittleBigPlanet, and PixelJunk Eden. I see no reason not to give this one a go when it comes out.

*Full disclosure: AJ Glasser (Writer of the article) was a pre-alpha tester on Ratchet & Clank: Size Matters.