Imitation is the sincerest form of flattery, as the old saying goes. What the old saying forgets to add is that the imitation is all the more effective - and a good deal less sincere - if your source material is largely forgotten. Gears of War may not have invented the concept of single-button cover systems (take a bow, kill.switch!), but since that was the game that made the mechanic so popular, no-one really cares about the one that did it first (get off the stage, kill.switch!).
In the case of Assassin's Creed Brotherhood's multiplayer, the overlooked source is The Ship - a Half Life 1 mod that eventually got its own commercial release, one that is now played by all of about four people. Unfortunately The Ship lacked sales, and as a result it largely went by unnoticed. This was something of a shame, as the core concept was excellent. Participants found themselves dumped on a commercial cruise liner, along with a large crowd of NPCs and human-controlled competitors. Each player was then given a target to hunt down and kill - an objective tempered by the knowledge that you yourself were the intended prize of another would-be assassin. Crucially, the AI characters were visually indistinguishable from their potentially human counterparts, leading to a stressful situation where everyone crawled around the map, pretending to be bots and fearfully peering over their paranoid shoulders.
The Ship is all but dead these days, but the game's spirit now has forebear of sorts. Barring a few changes, Brotherhood's multiplayer is a beefed-up descendant of the same old murder-em-up hijinx. A few things have been ditched, naturally. The Ship gave players a series of Sims-like needs that had to be catered for - notably a hungry belly and a leaky bladder - resulting in a near-constant requirement to stay on the move. The whole idea was to prevent camping and to keep the gaming ticking over at a nice pace, but since Brotherhood's matches are already fairly speedy, these redundant mechanics are nowhere to be found. Besides, it would probably ruin Ubisoft's carefully-crafted ambiance if you had to stop every two minutes to take a gushing piss all over Renaissance-era Rome.
Aside from the absence of potentially fatal toilet trips, Brotherhood's core multiplayer plays a lot like The Ship did back in the day. You creep about with one eye on your radar, desperately trying to find your target and hoping against hope that you won't get snuffed out by your unseen stalker. It's gripping stuff, and the whole experience draws heavily on the tense atmosphere that Ubisoft has perfected over the course of the franchise. Crowds have always featured heavily in the Creed series, but while we're used to playing the all-powerful predator lurking among the public, here you have to contend with the knowledge that there are up to seven other killers out there. Is that courtesan on the corner a rival player, waiting for their moment to strike, or is it simply another AI-controlled passer-by? Either way, you're going to find out soon enough.