Michael Pachter, video game analyst for Wedbush Securities, believes that these two games combined will sell 8 to 12 million copies total worldwide. If they’re great games, they’ll sell 12 million units total, which would put these two titles in the same sales league as previous titles’ stand-alone sales. Early press reviews have been mixed with Assassin’s Creed Unity receiving an aggregate score of 76/100 on MetaCritic.com based on 26 reviews, while Assassin’s Creed Rogue has received a score of 84/100 based on five reviews.

“The split is problematic, as it required two development teams and will likely require two marketing plans, but they had to do it because the co-op mode in Unity was too complex for PS3 and Xbox One,” said Pachter. “I am not really sure what sustains the franchise, other than the constantly shifting of historical settings. People love the franchise, no question, notwithstanding that the games are similar.”

That familiarity with the third-person perspective action adventure games has turned the franchise into a reliable annual video game blockbuster. Ubisoft has been able to churn out new games annually by using multiple development studios around the world. Nine studios had a hand in creating Assassin’s Creed Unity, which first began development three years ago. This process allows Ubisoft to deliver at least one new game every year.

With the growing installed base of 29 million next generation consoles (Pachter forecasts 17 million PS4s and 12 million Xbox Ones by year end), Ubisoft decided to take advantage of the advanced processing power to deliver new multiplayer open world gameplay for next-gen gamers with Assassin’s Creed Unity. Ubisoft producer Vincent Pontbriand said his team created a “shared experience” for up to four players to experience through exclusive heist treasure hunts and more complex narrative-driven Brotherhood missions.

“Players can invite friends that are online into their session and they can play together in the open world of Paris and find missions to explore,” said Pontbriand. “We’ve replicated all of the systems from the campaign experience like the fighting, the navigation and the interactions with the crowds of thousands of intelligent computer-controlled characters and opened it up to four players to explore as they like. We’ve also allowed players to customize their character’s costumes and upgrade their skills and abilities.”

The interactive Paris that players will explore is the by far the largest environment that Ubisoft has ever created for the franchise. The land mass of Paris is bigger than all the islands from the previous AC game combined. Beyond the larger surface area to explore, players can also enter landmarks like Notre Dame Cathedral, the Palace of Versailles and the Pantheon, as well as the catacombs.

Unity’s story spans the French Revolution and has protagonist Arno Dorian interact with historical figures like Napoléon Bonaparte, the Marquis de Sade, and Maximilien de Robespierre as he seeks to expose the true powers behind the revolt. The game also features key events like the storming of the Bastille. Ubisoft historian Maxime Durand worked with the team over the past three years to make sure the game was historically accurate.

“The Paris in the game is divided into seven districts and each has different visuals,” said Durand. “The characters have different animations because every district has a different set of social classes and jobs that people are doing in the street like broom sellers or shoe shiners or artists.”

Ubisoft isn’t abandoning the 160 million gamers who own PS3s and Xbox 360s worldwide. Assassin’s Creed Rogue is available alongside Unity, offering a completely different experience for action fans. Rogue is set in mid-18^th Century North America amid the chaos and violence of the French and Indian War. The game puts players in control of Shay Patrick Cormac, a fearless young member of the Assassin Brotherhood who switches sides in the epic war throughout history between the Assassin’s and the Templars.

The one element that has tied ever Assassin’s Creed game together is that gamers always played as an Assassin. Rogue turns the tables and lets players take control of the enemy from previous games, which opens up brand new gameplay elements, as well as a fresh arsenal of weapons. Set between the events of Assassin’s Creed III and Assassin’s Creed IV, Cormac’s journey of revenge spans New York City, the wild River Valley, a huge hybrid world that spans the Appalachian Mountains between the U.S. and Canada, and the icy cold waters of the North Atlantic off Newfoundland.

“If you’re walking down the streets of New York your enemies can be hiding in hay stacks or tracking you from above and they have weapons like smoke bombs and hidden blades,” said Karl Luhe, associate producer on Assassin’s Creed Rogue. “It’s a much more dangerous environment and the player needs to be on their toes.” Luhe said everything’s fair game, including using civilians and animals to turn the tide against the French. Players will have unique weapons like berserk darts and sleep grenades to aid them in their missions.

“Exploration is a key part to these experiences,” said Luhe. “It’s really beautiful exploring these environments within this huge hybrid world.”

According to Tony Bartel, president of video game retail chain GameStop (GME), Ubisoft’s decision to develop two original Assassin’s Creed games from the ground up shows that there’s a lot of innovation across both generations of consoles today.

Ubisoft already has its next historical adventures in development for 2015 and beyond, but for now gamers have plenty to explore.