The pair also explained that because the game was so radically different from its predecessor and that the scope and open-world gameplay was so different from the previous game, they opted for the project to be a numbered sequel as opposed to a spin-off that followed in the footsteps of the last numbered game, Assassin's Creed III. Ismail also stressed that they aimed towards a more historically accurate take on the era, including staying away from the stereotypical image associated with pirates, such as parrots, Krakens, and plank-walking.

Assassin's Creed IV: Black Flag producer Martin Schelling and Mission Director Ashraf Ismail both stated that they began the project in the summer of 2011, with a pirate game as their focus.