In an interview featured in the latest issue of OXM, Assassin’s Creed 3’s mission director Phillipe Bergeron detailed how co-operative play was going to be a core mechanic in Assassin’s Creed, until Ubisoft abandoned the concept.
"Before we knew about the Desmond story and Animus link, we had a huge co-op component in there," he revealed "But it just became too hard to do: the engine couldn’t support it, and then the metaphor we had above it didn’t support it."
"Co-op was one of those big things at the beginning that just didn’t make sense in the end," Bergeron said. "For us it was really part of the single player experience, to have in-and-out co-op, and in the end we never thought it made sense in the storyline that we had for the Animus."
As the story evolved to being more about Desmond and his intimate relationship with the animus, the co-op started making less and less sense.
"There was no way to reconcile having multiplayer or co-op in an ancestor’s memories," he explained. "Your ancestor lived his life in a certain way, so assuming you had branching storylines, it creates a paradox. It didn’t fit."
While I agree that co-op would make no sense within Assassin’s Creed’s main story setting, it was used nicely in the game’s eventual multiplayer modes.
Still, I have to balk at the idea that anything at all within Assassin’s Creed was done for story-telling purposes with the anticlimactic conclusion of the 5-year arc in Assassin’s Creed 3.