Singh used Unity 3D to create the level and recorded the video below entirely through HoloLens without post-production. He said the hardest part of the process was tweaking the game to work in a large outdoor environment, since HoloLens wasn't exactly designed for physically big games like that. We say all that effort's worth it, especially if you can find a Mario (or Luigi) costume to complete the experience.

Obviously, Singh can't release the game due to copyright reasons, though CNET says he's considering giving the code to other gamemakers. As for the rest of us? Well, we at least have Super Mario Odyssey to look forward to.