Mind u that each game has two leads: one being that guy, "Desmond" and the fact that the machine that the Templers are using forces him to live that life until they are finished with it. Altair was only accessed first because in him were the memories of the locations of the other artifacts. At the end of the game some else was being used before you as seen with the eagle vision. I wonder though, is the vision a curse or a blessing? Several cryptic as well as the doctors flat out death threats mean you’re as expendable as the person who wrote on the wall. Many locations drawn in the corresponding rooms show ancient temples and cities. In fact several devices were in the ocean, either from Atlantis or maybe back when we were Pangaea. They’re laid out way to methodically for my tastes.