It's Crackdown 1.5. Four player co-op is the big appeal for me.
I messed about on it last night hunting agility orbs and I'd forgotten how addictive it is...
Much like the first one; disconnect your brain, jump in and enjoy.
There is an annoying thing going on with the targeting mechanic in that you can be looking right at an enemy who has just climbed out of a car but you'll aim at the car.
The co-op only tracks the mission progress of the host but apparently (not tested it yet) all the orbs you get will save to your character so you don't lose anything.
Climbing up stuff is fun, running over countless freaks is fun, smashing enemies up with either your fists or whatever you can find is fun and shooting has a targetting issue but is still a laugh.
Much like the first one, it's something to play for half an hour when you get back late from the pub.