John Carmack, the chief technology officer of Facebook’s VR subsidiary Oculus, is stepping down this week. Carmack posted the news on Facebook today, saying he plans to focus his time instead on artificial general intelligence. He will remain in a “consulting CTO” position at Oculus, where he will “still have a voice” in the development work at the company.

Carmack will still work on some VR projects at Facebook, a spokesperson told Variety. In addition to general advisory tasks, for example, he will keep working on projects that maximize VR visual quality on lower-powered mobile hardware. However, he says that VR will “only be consuming a modest slice of my time” while he works on AI. “I have sometimes wondered how I would fare with a problem where the solution really isn’t in sight,” he said of the subject. “I decided that I should give it a try before I get too old.”

Carmack, also known for his work programming games like Doom and Quake, played a substantial role in the current generation of VR. He helped promote the Oculus Rift when it launched on Kickstarter in 2012, and he joined Oculus as CTO in 2013, leaving Doom studio id Software. ZeniMax Media, id’s parent company, later sued Oculus for allegedly misappropriating trade secrets to build Rift development tools. The two companies settled last December.

In addition to games and VR, Carmack has also worked on private spaceflight efforts through a startup called Armadillo Aerospace, although the project has been in “hibernation” for several years.

At Oculus, Carmack turned his attention to mobile virtual reality. He was known for his passionate and intensely geeky keynotes at the annual Oculus Connect conference, and he was instrumental in building the Gear VR, a phone-powered VR headset that was released before the consumer Oculus Rift and remains one of the most widely distributed headsets ever created.

However, recent comments from Carmack suggest he may have soured on VR development. In October, he delivered a “eulogy” for the Gear VR, which was effectively discontinued this year. And in a video for receiving a lifetime achievement award this week at the VR Awards, he said that “I really haven’t been satisfied with the pace of progress that we’ve been making” in VR.

Update 8:00PM ET: Added further context and statement to Variety.