My favorite series is
Assassin's Creed. I've played every single game aside from
Assassin's Creed III: Liberation. Only ones I haven't finished are
Altair's Chronicles - which is borderline unplayable, mind you - and
Assassin's Creed II: Discovery. You don't even have to doubt I'm going to delve into this fantastic topic.
First of all, I'm a huge history buff.
Assassin's Creed features important periods in history, even shining light on topics that your textbooks don't mention. I actually played
Assassin's Creed II when I was studying the Renaissance in World History. Needless to say, I aced it. It also introduced me to my favorite time period; the height of the Ottoman Empire.
I also love the story. Learning the story is arguably as in-depth as learning about the world of Tolkien's
The Lord of the Rings. There are currently five novels, nine games, four short movies, one film in production, about nine comics, an online game, and two editions of an encyclopedia. Needless to say, there are plenty of topics to learn about.
The story itself is an adventure into the lives of Assassins whose lives have been touched by the evil tendrils of the Templars. Each Assassin has given his life for the final goal; to assist Desmond Miles in stopping the destruction of the world. Ezio sums it up perfectly when he speaks to Desmond - a mind-blowing moment for me, by the way.
Ezio Auditore da Firenze said:
Maybe you will be the one to make all of this suffering worth something in the end.
The characters themselves are also masterpieces. Altaïr Ibn-La'Ahad is easily my favorite character in all of gaming. Even some of the more minor characters - La Volpe, for example - are amazingly developed. I've grown an attachment with nearly every character that has been branded a name in the
Assassin's Creed universe.
To put it simply,
Assassin's Creed is my favorite game series.