In an interview with IGN, Assassin’s Creed movie Executive Producer Pat Crowley revealed that 65% of it will take place in the present day, while the other 35% will take place in 15th century Spain.
Star Michael Fassbender, who plays convict Callum Lynch in the present and Assassin Aguilar in the past, may have explained why they switched the formula up from the games:
There are certain things that we absolutely want to respect in the game, but we also want to bring new elements to the game […] This isn’t a video game that we’re making. We’re trying to make a cinematic experience, so there are new things that we have to introduce.
Crowley also told IGN that they spent a lot of money on the movie to keep it from being just a clone of the game:
Often when movies are made of video games, people don’t spend the money, they don’t spend the time because they go, ‘They’re gamers. Just do the game on screen and they’ll like it.’ But we really feel, since often those haven’t been very successful, that we had to step up. We knew we had to spend money so that people wouldn’t feel like it was just a rip off of the game.
While the Assassin’s Creed movie “exists within the rules and the world that Ubisoft has set up that Assassin’s Creed can take place in,” Crowley adds that they created a new story respecting the rules to a point where a gamer could go, “‘I know this world.'”