John Carmack has been building a virtual reality headset in his spare time. He’s showing it to people behind closed doors at this year’s E3, tucked away inside the Bethesda booth, and described it as “probably the best VR demo the world has ever seen.” Click here to watch the video demos.

The goggle screens completely cover your vision, meaning the only thing you can see are scary corridors and flying heads. Character movement works more traditionally however, with players using a controller to walk around and shoot, while the goggles function as a head-tracker. If it ever comes to market as a consumer product, or even if the maker kits are reasonably accessible, it sounds like the perfect thing for hardcore ArmA(armed assault) players or flight sim enthusiasts.