Here's a VR text-input concept by Elevr. Using three dimensions you only need one hop from the center of a 3x3x3 cube to hold 26 letters, plus a space in the middle. http://elevr.com/keycube-3-torus-based-typing-in-vr/#h.a9zrf... (This shows the setup but it's not the final version, because eventually they realized that returning your cursor to the center after each character works better with muscle memory.) So use various controller axes to indicate positive-neutral-negative for three axes, and you have a letter. If you use chording you can type reasonably fast. There is quite a learning curve though.