But the developers of the eight main action-adventure games and countless side games had previously been very careful to not get too close to modern times.
"Assassin's Creed Syndicate," released Friday on consoles and November 19 on PCs, takes place in Victorian England during the time of the Industrial Revolution. Specifically, players will explore the city of London in 1868, a time of class turmoil and the beginning of disruptive change around the world.
Marc-Alexis Côté, creative director for "Assassin's Creed Syndicate," said the game takes place during an evolution from the old world ways into what people would consider modern history. London, one of the world's leading cities, underwent a huge influx of technology and people at that time.
"It is the heart of the game," Côté said. "The most important part of 'Assassin's Creed' is the minute you step in London, it is the first thing our characters say to each other, because they come from the countryside. They are just amazed by this new world."
Because the scenario is closer to current times than another other game in the franchise, and many buildings in London from the 19th century are still standing, Côté said it was important to portray the city as accurately and as fully as they could. The development team brought in two historians who made sure the London in the game was as close to the real-life 1868 London as possible.
Jean-Vincent Roy, in-house historian for game developer Ubisoft, toured current London to discover details from history that still exist today. He and the development team wanted to get a feel for how the city breathed, how the streets wound through the neighborhoods and how it might have felt to be there during the Industrial Revolution.
"The historical period, itself, was very appealing to us," Roy said. "The whole Industrial Revolution thing was something to be seen quite obviously in London at the time. The way tugboats appeared on the Thames. The way traffic is organized. All of these things were of interest for us."
Most major landmarks from that period are still around today. But 140 years ago, they were surrounded by a much different cityscape.
The Thames River was and still is the central part of London. In the 1860s, it was a major artery for trade, but it was also a dividing line between the classes.
Parliament, the English royalty and white-collar workers occupied the north side while the south shores were home to industry, slums, and blue-collar workers. Côté said the area south of the Thames in the 1860s would be unrecognizable to modern Londoners.
"It was mostly an industrial area back in 1868, and nowadays, it is completely different," he said. "This is the part of the city that feels very new and fresh -- especially with its more industrial side, all the smoke on the south shore, and still a bit of countryside, which is absolutely nonexistent today."
Much has been documented about how the city looked and behaved back then, which helped Ubisoft's development team visualize the environment they wanted for the game.
Historian and author Judith Flanders, who has written books about the Victorian Era, worked with the Ubisoft Quebec studios on some of the finer points of London.
"What was amazing seeing those clips (from the game) was seeing all the stuff that I'd read but obviously never seen because I'm not 140 years old. And thinking, yes, of course, that's what it looks like," Flanders said. "Stuff that I hadn't thought of. It was stuff the designers had thought of, and they got right."
Flanders said some historically accurate elements had to be sacrificed for game-play purposes, including details that happened close to, but not in, 1868.
But other things definitely need some tweaking.
"The names of the pubs stank. The names of the pubs were dreadful," she said. "(They) sounded like cheap 1990s wine bars. We really worked on the names of the pubs (from a published list of names from the 1850s)."
Côté understood the meticulous way people might look at a city that they recognize from personal experience. Its more modern setting also required more power from gaming consoles, which also created its own hurdles.
"It was more challenging, because we've been avoiding vehicles for quite a while in the 'Assassin's Creed' experience, focusing more on foot navigation and everything," he said. "When we choose to represent a city like London that had millions of vehicles in it ... we could not represent this city, this era, at this time without vehicles."
And it wasn't enough to make the new game look like 1868 London. They also wanted it to sound like 1868 London, including variations of speech between characters. Flanders said how people spoke to one another depended on class and gender as well as personal relationships.
"I spent more time than I care to think, using historical slang dictionaries, to find the nine million synonyms for being drunk," he said.
Historical accuracy is great, but ultimately the goal of the game is for the player to immerse themselves in a virtual world and have fun. From the historians' perspective, getting people to learn about Victorian England is just an added bonus.
"The game is super fun and a very cool way to discover the period," Roy said. "If, by ... having a blast running and driving and touring around London at that time, anyone who picks a book and wants to learn more about the period, from my own perspective as a historian, it is a win."