The eight-player mode that Ubi had set up at its pre-E3 event is a sort of directed free-for-all. It puts all of the players--each of which is dressed up in a unique pedestrian skin that you'll see wandering around the city, like a banker or a courtesan or something. So out of the players, you'll look unique. But there are plenty of AI-controlled bystanders on the street that look just like you. This, as they say, is key.
The mode is structured around contracts. You'll get a contract to kill a specific player, and a ring near the bottom of the screen gives you a basic pointer in the direction of your prey. You'll also get their picture, so you know which character type you're after. The goal is to get to your target and kill him. But other players will be after you, and the better you do, the more heat you'll have at once. At one point, I had three players trying to track me down. The way to avoid trouble ties into one of the basics of the Assassin's Creed franchise: maintaining a low profile. If you run around or act like an ass, your location is revealed to players that are chasing you, as well as your current target. This makes everything a lot harder.
You can stay hidden via the classic AC maneuvers, as well, like blending into a crowd or sitting on a bench. But since your hunters have pointer to your direction, you'll need something a little extra to throw them off of your scent. That's where the game's perk-like system of special abilities come in, like a smoke bomb that lets you get the heck out of there, or another ability that changes your appearance for a brief period of time. Another turns some of the non-players near you into your exact character type, making you hard to pick out of the crowd. If a player kills an NPC, he loses the contract, leaving you safe. You can also hit a button to kick your assailant over when he gets close, a humiliating move that gives you some time to move away.
The structure of the game makes the slow default movement speed that the series has had all along make more sense. It becomes easy to move like the AI moves and generally look like you might be just another computer-controlled citizen of Rome. Players that run around like lunatics or jump off of roofs give themselves away immediately and look like fools. It all comes together to make a devious, fast-paced murder mystery, where you're never quite sure if the person walking in your direction is going to silence you with a hidden blade to the back.
Though this game is set during the Assassin's Creed II timeline, it'll happen in a new city. And there's some "real-world" justification for all of this violence, too. It seems that members of Abstergo--the Templar front corporation that comprises the bad guys of the series--are training to become better killers, and they're doing so by jumping into memories and playing these training games. There will also be a single-player component built around Ezio's time in Rome. There aren't too many details out there about that stuff just yet, but it sounds like you'll build your own brotherhood of assassins and fight against Templar forces in Rome.
Stabbing human opponents, especially ones that never had any idea I was even onto them, was extremely satisfying during the two rounds of Assassin's Creed: Brotherhood that I played. Between that and the promise of at least some ties to Desmond Miles' real-world, outside-the-Animus issues, Ubisoft could be onto something really special here. We'll have to see how the other modes and options pan out before we know for sure.