Check Out This Free to Play SUPER MARIO BROS VR Demo
A fan made game demo, titled Walk-O-Motion, brings players to the first level of the classic Super Mario Bros game to run through and look around with their own free will!
There are hidden things for you to find in the background, all listed as a challenge at the end of the level. Go down the pipe to the underground coin collection, jump on goomba's, or just do whatever you want to do!
It seems like a fun thing to try out, even if it doesn't become a full game. Check out the playthrough done by YouTuber Nathie.