I'm playing through AC: Syndicate right now (Victorian England) and was discussing the game with my wife as a potential resource for one of her class assignments. The assignment is to come up with a potential topic for a fake class. Since talking about it I've been wondering what /r/AskHistorians thinks about the games and couldn't find much by searching.
So, how do the games stack up to the historical figures included as major characters? How well do they do at depicting specific events? How does the historian community view the games overall?
Anecdotal I know, but: when Assassin's Creed II was released I was working on my undergrad dissertation. Coincidentally, it was mostly based on quattrocentro Florence. My supervisor himself had a special interest in the Florentine Renaissance, and well, I showed him a little of AC II, with which, he was reasonably impressed, but not really for the reason's you are asking about. The Renaissance is a fantastically complex period, which thanks to the diligence of Florentine businessmen and various chroniclers we have a vast amount of written information about, and, thanks to the fantastic permanence of its (highly impressive) architecture, it's a city which hasn't changed as much as say, New York or Boston - or even London for that matter.
The point was, AC II did a remarkably fantastic job at modelling much of the city - it's certainly not perfect, but the constructed city does bear a striking resemblance to the city I studied. My supervisor was duly impressed with the excellent modelling of most of the churches, some of the most important palazzos, and the distinct difference between the Cathedral side of the city and the Oltrarno quarter. (admittedly several key buildings are missing - Including the baptistery of st. John which is a pretty key element of Piazza del Duomo, that predates the cathedral itself - and the city layout is condensed a little)
In terms of historical events, its a little different. Certain figures are there, the first threads of the games plot begin with the Pazzi conspiracy, which was an actual event, which happened in much the same way as it does in the game, albeit, it was unlikely that Lorenzo il Magnifico had a saviour in the form of a disgraced nobleman turned assassin named Ezio, or that the Borgias had much to do with it.
Recently, when AC Syndicate came out, the Guardian ran an article based on discussion of a playthrough of the game with Alanna Harris, a Teaching Fellow in Modern British History at Kings College London, which makes quite interesting reading and sums up many of the problems (and things got right) of the game.
http://www.theguardian.com/technology/2015/dec/09/assassins-creed-syndicate-historian-ubisoft