The first Saints Row was a pleasant surprise. Sure, its trying-way-too-hard urban-themed take on the open-world genre may have been a bit ridiculous, but its solid gameplay mechanics (notably, the shooting system) and spiffy graphics (given that it was the first game of its type on XB360) made it easy to like. Saints Row 2, though, faces a slightly tougher task: following the behemoth known as Grand Theft Auto 4. Will people still care about this fledgling series? We’ve covered Saints Row 2 plenty already, but we’ve only recently gotten our hands on perhaps its biggest weapon in the open-world war zone: online co-op play.

The setup is nice; while GTA4 has co-op-specific missions and Mercenaries 2 has a limited form of co-op in the main game (don’t tread too far from your buddy), Saints Row 2’s setup is wide open -- think Crackdown. A second player can pretty much jump into the game at any time -- complete with any unlockables and customizations in tow -- joining the host’s game at whatever state of progress and difficulty is set. The joining player can’t immediately jump into a specific mission in progress, but the beauty is that once in, you can do whatever you want: jack some cars, get a unit of angry army dudes chasing you, or just futz around town.

Once both players are in, if someone then starts a mission, a message pops up asking the other player if they want to join. If so, the mission starts, specifically tuned to accommodate two players -- meaning more enemies and different A.I. behavior (hence the no midmission joining). The cut-scenes don’t change in terms of content; the only change is that they feature each player’s respective character in the starring role. You are simply playing the missions with a bud, and when you leave the game, all the progress carries over. In fact, if you complete a few later-in-the-story missions with a friend in co-op, you have the ability to skip those missions when you reach them in your own single-player game.

The other big portion of the whole co-op thing is developer Volition’s acknowledgment that two players loaded up with weapons can’t help but devolve into friend-on-friend shootouts. The twist here is that if you kill the other player, they have the option to respawn into one of two side games: Death Tag or Cat & Mouse. Death Tag is what you’d imagine: a time-limited showdown in which you try to get the most kills on the other player. You spawn relatively close to each other but have free run of the city and any vehicle that you can jack at your disposal. Cat & Mouse, meanwhile, puts one player in an attack chopper and the other in a sports car. The chopper pilot, as you guess, just has to take out the car driver. The car driver’s goal is to get through as many checkpoints as possible before getting shot up to all holy hell, and once that round is done, the roles reverse, with the player who racks up the highest score winning the contest.

These make for a couple of fun diversions for a game that’s looking good, from its extensive character creator (you can be male or female, emaciated to obese, and take on such personalities as haughty, smarmy, or evil) to its loads of minigames (including flashing and streaking) to a soundtrack featuring a killer ’80s/’90s mix station, headlined by the inimitable "The Final Countdown." The only part of the package that remains a mystery before next month’s release is full-on multiplayer, but already, Saints Row 2 has plenty going for it.