1. Google cardboard.
https://www.google.com/get/cardboard/
2. Microsoft kinect.
https://www.microsoft.com/en-us/kinectforwindows/
3. Virtuix omni.
http://www.virtuix.com/
4. Bowman, D.A., Koller, D., Hodges, L.: Travel in immersive virtual environments: an evaluation of viewpoint motion control techniques. In: Virtual Reality Annual International Symposium, 1997, 1997, vol. 215, pp. 45–52. IEEE March 1997
5. Bowman, D.A., Kruijff, E., LaViola, J.J., Poupyrev, I.: An introduction to 3-d user interface design. Presence: Teleoper. Virtual Environ. 10(1), 96–108 (2001)