id Software co-founder and technical director John Carmack has confirmed that the studio has closed down its mobile gaming operations in order to focus on the development of Doom 4.
Carmack revealed his studio's decision during his keynote speech at this year's QuakeCon.
"We did make the decision to close up our mobile development, which saddens me a lot, in that I love doing the mobile work," Carmack said during his keynote. "But we had some developers on there that we wanted to bring on to the Doom 4 project.
"I hope we get back to mobile in various ways in the future, but the big real aim is blockbuster, AAA titles, and for id that means Doom 4."
Carmack revealed that his studio is sitting on a finished iOS project, but gave no more details. The studio head also stayed silent on the topic of Doom 4's release date, saying that the project "will be done when it's done", and that "every decade, there will be a Doom, but hopefully we can do better than that".
Doom 4 has been the subject of several cancellation rumours over the last two years. Last October, word spread that Doom 4 was "indefinitely postponed. At the time, Bethesda replied by saying: "Games are done when they are done, and no title under development at id has been postponed--indefinitely or otherwise."
The publisher was again forced to reassure gamers of Doom 4's existence earlier this year, saying: "Doom 4 is not cancelled. When we are ready to talk about it, we'll let folks know."
The game's existence was first acknowledged in May 2008, when the developer sent out a press release stating that production had begun on the game.
At the 2011 Electronic Entertainment Expo (E3), Carmack said that the core team on Rage would move to Doom 4 development following the release of its latest shooter.