World War II
Though Unity did touch on the setting through its time anomaly segments, it’d be cool to see Assassin’s Creed break free of it’s traditional geographically-driven structure and take on a more global conflict like the Second World War. The series has hinted at Templar-influence playing a role in the war and a more-ambitious adventure that sees you globetrotting your way across the various fronts of the war could be the kind of reinvention that Assassin’s Creed needs at this point. The game could see you sabotaging enemy defences and paving the way for Allied forces or even enter active war zones to eliminate valuable targets. It even go the Rogue route and see you start the game on the side of the Nazis.
There is the question of how rapidly advancing firearms technology would impact the series traditional gameplay here but I would argue that the moment Assassin's Creed 3’s Connor Kenway charged headfirst at a line of riflemen, the series’ lax commitment to realistically depicting firearms became VERY apparent. Jokes aside, Ubisoft do genuinely need to overhaul the role guns play in the series and perhaps a World War II game is just the excuse they need.
