3. A New Age
This one was a bit obvious, wasn't it? To date, Assassin's Creed's most defining character has been Ezio Auditore. So the moment he became an Assassin has got to be pretty damn defining. Innocence is not something we usually associate with the life of an Assassin- after all, they kill people for a living. But they have to start their mindless killing somewhere. For Ezio, that moment was right here. His father and brothers had been taken captive, and the only thing that spared him the same fate was the delivery of a small bunch of letters. Then, he is thrown into a situation were his family's lives are dependent on the contents of a small chest - which understandably proves frightening for him, let alone confusing. However, most importantly, what Ezio finds in the chest dictates the rest of his life. The moment he dons the hood for the first time is the moment his childhood innocence is lost. In doing so, he chooses a side in the most long and brutal war known to man. Arguably, this is the most important part of the Italian's life, and therefore the most important of the games he's involved in.