They bring out brotherhood because what i think, yes it's a good game but it felt like it could have been brung out as DLC for the second game as it was basically the same everything except for new missions, multi-player(which i found pretty decent) and Assassins that work for you(again decent.)
I think Ubisoft just wanted a bonus after AC2 to be honest and anyway I'm still a fan and I'll buy definitely buy the 3rd one, when it eventually comes out.
We can count AC:Brotherhood as an expansion pack for AC2, but AC3 will be a new thing it seems.
It's not an "expansion pack" if it continues the main story.
There are some big developments in the AC storyline that occur in Brotherhood. If it's "an expansion pack" then how come players HAVE to buy it to keep up with the story?
btw players HAVE to buy an expansion pack because it contains DEVELOPMENTS in it. xD
I agree, though, that Brotherhood is an entire game on its own, but it's also an expansion pack in the sense that it expands and extends the story of ACII, rather than being something new as sequels more often than not are (i.e. compare ACI to II, then II to what has been said about III).