I should probably explain my position. 
Summary
The only reason AC2 was decent in my opinion was the craftsmanship around Ezio. I couldn’t really get into the growing storyline they plopped him into though, and how it concluded annoyed me beyond explanation. And as it went on, it seemed like they were refusing to expand beyond the foundations of AC. Which is understandable in some degree. You have to remember your game’s origins (the assassinations, the assassins etc) but hardly anyone wanted to play the same game pattern over and over again for 6? 7? Games. If that wasn’t enough of a problem, when games like AC3 and Black Flag came around, which offered in seemingly great story lines or mechanics (such as the American Revolution or commanding a pirate ship) they fumbled the ball by failing the execution. For example, in AC3 you get from point A to B so fast that you can’t get attached to anything, and it feels like the “war” is nothing more than a spat at a border. The characters other than your main character are flat and thrown in to remind you it is a historically centered game about Assassins. In Black Flag, they forgot about story and character almost entirely to focus on scenery and gimmick, so when you jump into what appears to be the lake, it turns out to be a shallow puddle. They aren’t terrible in any means though, I wouldn’t say that, just not something I personally would play in any free time. I don’t mean to knock anyone’s favorites, just wanted to express my opinions and why I might have felt that way about the games.
But I feel like, as someone who felt that way for the other games, in AC:O, they really seemed to have learned from their mistakes. I mean I would prefer that in AC:O they spoke more Greek (even should it not be the Greek of that time) but it is an incredible game.
And yea, I think the Viking information was a huge leak when Odyssey came out, so you might have heard about it then. I remember hearing about it then, but having bad impressions of the AC games, and despite loving the Scandinavians and Vikings to pieces, pushed it aside. lol
