In Dallas, last month, I spotted a big inflatable igloo. It had been erected by a company called Microvision on the exhibition floor at QuakeCon. Inside of it, I discovered, was a man holding this gun.

The Microvision people were getting QuakeCon attendees to line up for Project Tuatara, an experimental technology designed to be used with any mouse-and-keyboard first-person shooter.

They rigged a gun-shaped controller with a projector that turned the part of the igloo's inside walls toward which the gun was pointed into a part of a video game world. That world was programmed to exist in a fixed orientation in the igloo. Moving the gun — and the attached projector — would let us see other parts of that world. Pointing the gun up projected the video game world's sky onto the ceiling. Pointing east showed the part of the game's level that was to the east; pointing west showed the west. They had created a sort of projected virtual reality that needed no headset.

For this demo, they were using the released PC game Operation Flashpoint. The Microvision people let me go inside the igloo to check it out. Here is what I saw:

There is no release date or price for Project Tuatara. And you don't need the igloo. Any wall will do.