Preparing the PlayStation 4 and Xbox One versions of Call of Duty: Ghosts for launch alongside the other versions proved to be a "logistical nightmare", Infinity Ward has admitted.
Talking to VideoGamer.com last week, executive producer Mark Rubin explained that developing for six platforms was a "brutal task", while the decision to layer a new engine, new story and new world on top was "maybe not the wisest choice".
"It's been a massive challenge for us," Rubin said about the development of Ghosts on PS4 and Xbox One. "We've done a launch title before, but trying to do two launch titles and continue to do the current-gen and PC was a big logistical nightmare for us.
"We ended up having to really... we hired a lot more people for one, but we grew significantly. We're actually about 150 people at the studio now and it used to be about 70-80. But as far as how [Ghosts] is going specifically, I think we're in a really good spot. We've basically gone gold on everything. We're working on a few additional patches for launch, but we're in a good place.
"It was just a brutal task to get there. To have to not only do two new next-gen consoles, two old-gen consoles, PC and do a new engine and do new content based on a new story and a new world, and doing so much more new stuff, was maybe not the wisest choice, but it was definitely artistically what we wanted the choice to be."
Despite the difficulties, though, Rubin explained that Infinity Ward didn't want to pass development of the next-gen versions on to another studio.
"We weren't going to accept someone else doing current-gen or next-gen for us," he continued. "We wanted to do both. We wanted to make sure that we were the ones who did it. We knew it was a lot of work - and it turned out to be a lot of work - but it was definitely what we wanted."
Optimising the Xbox One version clearly proved too much for the developer, however. Last week, Rubin explained that the Xbox One version of Call of Duty: Ghosts renders at 720p, with the PS4 version running natively at 1080p.
Call of Duty: Ghosts launches today on Xbox 360, PlayStation 3, PlayStation 4, Wii U and PC, and on Xbox One next Friday, November 15.