John Carmack is enough of a rock star in virtual reality circles to fill a room at a conference, even if all he is doing is just staring into a VR headset and criticizing apps.

Carmack, an Oculus technologist who helped design a lot of the technology that’s inside Samsung’s Gear VR, has begun his live reviews of a bunch of games and apps. He’s sitting in a crowded room with hundreds of people at the beginning of the Oculus Connect event at the San Jose Convention Center in San Jose, California.

Carmack is the chief technology officer at Oculus and co-creator of first-person shooter games like Quake and Doom, and he’s a gaming pioneer. He can also be brutally honest with his feedback, either in public or in private. He will deliver the closing keynote speech at Oculus Connect on Friday.

“We are at this wonderful moment,” he said at the outset. “I’m not allowed to say exactly how many have sold, but the Gear VR has succeeded beyond anyone’s expectations. The field is out there. So it is up to us to play the game well.”

He insisted that his opinions were his own and were not official Oculus views. He said he believes that many VR apps could benefit from some design-related tips, technical fixes, and suggestions about how to make the experience more comfortable.

“There are tons of exciting stuff about what will come. This is my major theme. We can do a lot right now with Gear VR that is good enough to deliver a lot of value,” he said.

Carmack also noted how initial analytics have come back to reinforce some of his suggestions about designs.

“High end gaming has taught us a lot of bad lessons about this,” he said. “You will play for an hour or a half hour, and so a minute of loading time is OK. It will put people off and I can say for an absolute fact they will stop if it takes too long to get into it.”

He looked at a VR player app at the outset. He said that deep blacks cause a smear problem on a OLED display like in various Samsung smartphones that are used with the Gear VR. A high saturated color like a full white has issues with flickering that causes eye strain, he said. A lot of his other comments were similarly technical.

“Too often we design in a realm of mathematical points rather than pixels,” Carmack said.

He said there’s a constant tug between crispness and smoothness in 3D art. He said art should be properly filtered because you are always moving your head in VR. Some things that look good when static look bad when in motion in VR, he said.

“We are learning as we go,” Carmack said. “Some of this will be my random comments.”

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