Assassin's Creed 2 was supposed to cover Brotherhood's entire plot, but that was "way too ambitious to deliver properly" in just one game
Even after all these years, Assassin's Creed: Brotherhood is arguably still the peak of the series. After Assassin's Creed 2 sanded off the clunky edges of the original game, Brotherhood offered a natural continuation of Ezio's story and expanded gameplay elements tied to his increasing leadership of the titular assassins. It's no wonder the sequel seemed so natural, since Ubisoft had apparently planned for the events of Brotherhood to be part of the plot in Assassin's Creed 2.
"When we designed Assassin's Creed II, Ezio's story arc was roughly from his birth to him becoming the mentor," Jean Guesdon, a series veteran who now serves as head of content for the franchise, says in an interview for Retro Gamer #287. Ezio's ascension as the mentor of the assassins' order would ultimately occur near the end of Brotherhood, just before the game's climactic final chapters.
There's no telling how the story would've changed or been condensed if it had been told within a single game, but it sounds like the developers themselves soon decided that wouldn't be possible anyway. "In practice this was way too ambitious to deliver properly in one game developed in two years," Guesdon continues. "But these original ideas allowed us to develop his story through the next two games."
Ezio's story would ultimately conclude in Assassin's Creed: Revelations, which launched a year after Brotherhood. The Ezio trilogy would start Assassin's Creed on the path of annual releases that the series would follow for years, making even the two-year dev cycle that Assassin's Creed 2 seem luxurious by comparison.
By this time, Ubisoft was already starting to spread development across multiple studios in order to release new games faster. "The games are not developed one after another," according to Paul Fu, another longtime series veteran who most recently served as creative director on Assassin's Creed: Black Flag Resynced. "They are always cascaded so that we can work in tandem."
"At first we made sure to keep the creative and production control in Montreal, where the experience was, but giving mandates to other Ubisoft studios in order to make them grow," Guesdon continues. "This is how, year after year, the basin of AC developers grew in terms of size, but also experience, allowing us to send more and more ambitious mandates to remote studios."
That style of development has made possible epics like Assassin's Creed Valhalla and Shadows, each of which absolutely dwarfs even the combined scale of Assassin's Creed 2 and Brotherhood. I still miss the days when the series was a little more constrained in scope, but I guess I'll always have the Ezio games to go back to.
Check out our rankings of the best Assassin's Creed games.