Natural locomotion is for hand usage though as far as I understand. That is to say I can stand still and move my hands and it would still move forward.
Immersion with the ability to walk and run in top-rated VR games is more of my goal... here's a video I made of me using my manual treadmill with PC games with an arduino+ Treadmill sensor.
https://www.youtube.com/watch?v=R7vi-QdTzfc&t=50s (me doing it with PC games in Kingdom Come Deliverance)
Right now setting my goals on Half-Life Alyx, Skyrim, etc...
True, but I recently found out that pressing your elbows against the holding rails of the treadmill helps reduce accidents and motion sickness since it gives you some sense of orientation, but I haven't tested it for long runs.
Interesting, but I didn't see the actual video of it working. So far I've seen several ideas for a solution but none of them made a video of it working naturally on a treadmill.
Vive Trackers seem like the least clumsy solution. There's AgileVR. But in both those solutions I didn't see if it's possible to script such a solution with those devices. I don't wanna undertake something technically impossible.