As you rebuild Rome you'll have the option to rescue and recruit street outlaws into your brotherhood, eventually customising them with specific outfits, armour and weapons to boost your cause.
As you recruit novice assassins, Ezio will be able to train them up by sending them out on assignments around Europe, via a unique animus interface. This is a real gem for fans of the conspiracy narrative hidden throughout the last game's glyphs, and offers plenty of nods at real historical occurrences.
One mission, for example, has you helping Henry VII deal with a Templar conspirator, Margaret of York. Due to her ties to the Pope the English King can't have her killed - but your assassins will promise to make her "disappear".
Assassins will gain experience with each mission completed, and the animus displays a helpful percentage meter - which shows your chance of completion based on the ability of the members you've tasked to the mission. Basically, it's like a miniature strategy game within Brotherhood.
When you're not micro-managing your foot soldiers and looking at stats, your trained Assassins can be called on at any time with the press of the right shoulder button - an ability you can only call on when one of several 'tokens' are cooled down and ready for use.
This changes the way you approach missions in a big way. In one sequence, you're tasked with quietly tailing and assassinating a templar banker, Juan Borgia, as he strolls through a Pagan party. As Ezio scrambles over walls and hides in the shadows, you can use your Assassins to stealthily remove enemies from your path, or even start a fight so you can sneak past undetected.
The assassins inject a whole new layer of strategy into missions. They feel like a powerful and valuable weapon, especially considering that when they die, they're dead for good - not a small loss when you've given your all to train them into deadly warriors.
The Brotherhood system is just one example of the quality and scope you can expect from Rome, which is massive, varied and simply a joy to explore.
The sandbox is what AC: Brotherhood does best. Ubisoft claims you could spend even more time exploring 2010's game than last year's big sequel - no small claim when you're talking 20-plus hours of solid gameplay - and it's telling no lies.
Rome - a predictably beautiful and epic metropolis three times the size of AC2's Florence - is split into districts, each occupied by an intimidating Borgia Tower. These represent of the Borgia's stranglehold over the city, and before you can start rebuilding shops and recruiting assassins you'll have to destroy them as a statement to the people.
You do this by first taking out each tower's Borgia leader. Sometimes they're strolling carefree along a patrol route, other times they'll be sat snug indoors flanked by a group of axe-wielding protectors - it depends what mood they're in at the time.
Either way, once they're put to the business end of your blade you're off for a quick climb - and spot of arson - at the top of the tower, following which the surrounding area is tactically transformed in your favour and you can start rebuilding Rome.
It's a bit like GTA: San Andreas' turf wars - and just as satisfying. Reclaiming Roman districts and rebuilding their shops (which in turn earns you a regular stream of income) is compelling in the same way that PS3's InFamous successfully layered strategic turf wars over the usual side quests and hidden collectibles.
And it's not as if Broterhood is lacking in the latter either, with guild missions (of mercenary, courtesan and thief varieties), shop quests, Templar targets, flags and the aforementioned Brotherhood management filling the streets.