But this isn't the third in the series by any means; it's a direct follow-up to AC2, the extension atop the series' single-storey flat of a plotline. It's a rough metaphor, but what I mean to say is that the game uses all the same architecture - both literally, in the setting, and figuratively, in the gameplay, look and writing.
The game doesn't change its footing drastically from any of the preceding titles. If you already thought the plotline felt like something Dan Brown wrote on the back of a beermat then you're in for more of the same, albeit a lighter version of what you came across in the last game; the modern-day plotline essentially hovers around the material of the sequel without making much leeway. It's not a serious criticism for anyone used to the franchise's established tendency for taking mere baby-steps when it comes to solving the mystery of what on Earth is actually going on. But Brotherhood is a bit more close-lipped than its siblings, cementing its status as an in-between title that bridges the gap between AC2 and the future AC3.
On the other hand, Brotherhood does successfully join up the game's two plots. The twin storylines of the present-day Abstergo runaways and the historical Ezio all end up funnelling back to Rome and Monteriggioni. The last time we left our contemporary gang of assassins, Desmond and friends were legging it from the Templar-run Abstergo facility. Now they've road trip'd their way to the ancient home of Ezio in Monteriggioni, setting up camp there in an attempt to use their home-made Animus machine to filter through Desmond's genetic memories and find out where the Apple of Eden is before the Templars swipe it. Often you'll be brought to the same place in two different eras, tying the present and past together in a way that neither of the earlier games were able to do coherently. That's the main difference between the original sequel and Brotherhood, right there: this game is tighter, to the point.
AC2 started its story off at a slow jog, with a purely functional introduction that slowly nannied you through the basic movement controls. Brotherhood, on the other hand, hits the ground running - hurtling you into the centre of the supernatural plot that you found yourself in at the tail-end of AC2. The result is a far more concise plotline that immediately marries the game's penchant for bizarre mystical stuff with its devotion to the historical setting.
But the game retains its unblinking focus on Ezio for the most part. AC2's puzzles are largely absent. You'll remember the ones I mean - the cryptic interrruptions that had you finding hidden images in paintings by hovering a cursor across every inch of the canvas. Similarly, the modern day Desmond story only really forms the basic bookends to the historical meat of the game. You'll be able to pop out of the Animus whenever you like, but it's not necessary to the plot beyond the bit of flavoured banter you can have with your gang, and the ability to explore modern Monteriggioni. Actually, it's a bit of a bizarre system: The second you step outside of the confines of the building to explore a countdown timer will pop onto screen, giving you ten minutes before you're instantly teleported back to your base - so any thorough exploration will inevitably be cut short.