Historically, Assassin's Creed games have launched for PC several weeks, sometimes months, after the console versions hit store shelves. This is because the PC version of each game has always been the last version the team at Ubisoft Montreal works on, Assassin's Creed 4 lead designer Jean-Sebastien Decant told Polygon.

The first Assassin's Creed, launched in 2007, saw a six-month gap between the console and PC release. Assassin's Creed 2 and Brotherhood both had a four-month release gap between the two versions, while Revelations for PC launched two weeks after its Xbox 360 and PS3 versions. Assassin's Creed 3 at first seemed like it would see all versions launch simultaneously, but its final launch on PC was almost one month after its console debut. The Wii U version of Assassin's Creed 3 also launched a little more than two weeks after the other console versions.

Earlier this week, Ubisoft confirmed Assassin's Creed 4 would launch on Nov. 19, nearly three weeks after its launch on Xbox 360, PS3 and Wii U and four days after its PlayStation 4 launch.

Decant explained that Ubisoft Montreal will begin development on one "master version" — essentially the first version the studio makes, usually for one console — and focus on it until it's finished. Then work begins on all other versions after, with the high-end PC version made last.

"It all depends on what is the master version," Decant said. "If for instance, the [Xbox 360] version was the master version, or the PlayStation 3 version was the master version, then we'd need a little bit more time to adapt it for the PC. But we need to finish that other version first."

Because the PC version is the last to be made, the team needs those extra few weeks to make final tweaks and guarantee a highly polished experience, he explained.

For Assassin's Creed 4: Black Flag, Decant said the master version was the current-gen console version — both Xbox 360 and PS3 SKUs were developed simultaneously on the Anvil game engine.

"The technology goal we had [for AC4] was for the current-gen," Decant said. From there the PS4 and Xbox One and the Windows PC versions were made. "You need to finish one and make sure that it's clean before you can then finish the others."