Yesterday, Call of Duty: Ghosts introduced the first playable female characters ever featured in Call of Duty's multiplayer campaign. The change, Activision CEO Eric Hirshberg tells Polygon, has long been one of the most requested features in the game: "If I had a billboard chart of requests, this would be near the top of the charts of things we hear from our community," he says. "It's certainly something I've wanted to do for a while. We have a lot of female players that want to play as female characters."

So why did it take so long? The reason, Call of Duty: Ghosts developer Infinity Ward's Mark Rubin says, was technical. Female characters require their own set of animations, and Ghosts' designers needed to account for the fact that female characters' smaller size might have made them seem harder to target — even if the hitboxes were just as big. "We actually had to sort of bulk up their gear a little bit to compensate for the fact that they're smaller," he says, "so that there's no perceived advantage."

In this case, he says adding women made sense because of the extensive character creation tools that were being put into Ghosts. But the announcement comes after years of developers explaining the same idea over and over: that putting women in games is just too hard. In 2010, Battlefield: Bad Company 2's producer said that adding new models and animation would "basically double the amount of data and memory for soldiers that would need to go into your game." After fans called for the FIFA series to include women, a producer said it would probably happen in the future, but that it would require developers to change the game's physics and add "a lot of new models and hair styles," making it unlikely in the short term. Many lesser-known games are male-only for the same reason.

As Ghosts proves, it's certainly not impossible to add female characters — nor do most developers say it would be. Instead, it comes down to priority. Crackdown 2's women were cut because the extra memory they took meant the team "would've needed to massively reduce other sections of the game." Bad Company 2's producer cited things like destructibility as more important than letting players pick a female character.

Assuming that developers really would have to make huge trade-offs to add a second gender, gameplay generally provides more lasting value than character models in a long-running competitive multiplayer series. Unfortunately for women, that one gender in virtually all games will end up being male, whether we're talking about the quasi-realistic world of Battlefield or a pure fantasy like Crackdown. But at least with Ghosts, one of the biggest franchises has decided that lifting the combat ban on women is worth adding a second set of animations.