Well , thats something thats pretty complex to do , and I dont think Ive ever seen anyone here do it before , though I have seen it discussed. And from the new Mario Galaxy game it looks like Myamoto found a proper way to do it and based the whole new Mario game on it , though it looks like the gayest Mario game to date , and this is coming from a big mario fan. I would say , the easiest way would be to rotate the level around the player and have the player do fake walking , of course if your looking to implement something like this on a big or full level , it might get hard and confusing. You can also just do traces and do vec_rotates or something depending on where the trace hits. This are just ideas , as Ive never done such a thing , I once made movement where the player could walk all around a cube , and I actually got it working pretty good , but in the end the camera coding was too much for me and I gave up the idea. Good luck with your project.
