The current hype thing

Virtual reality (VR) put the user in a virtual world where it is possible to look around by turning your head. It might also be possible to interact by using physical movement.

The current cool way to look at a Virtual reality is to use some form of head-mounted display. A less cool way is to use normal monitors and a head tracker like TrackIR.

VR sickness
When using VR one might be effected by a form of motion sickness that has been given the name VR sickness. Symptoms can be for example headache, nausea, vomiting and disorientation. Research is still being done on why VR sickness happens. One theory, the sensory conflict theory, posits that conflicting sensory inputs to the brain confuse it. If the headset is a little of you might look down a bit in the virtual world even your own vestibular system say that your head is level. When you look around the game might loose frames and your brain can not match the turning of your head with what you see. Not knowing what is wrong your body kickstart all the emergency systems in has in the hope that one of them will solve the problem.

The goal as a developer is to lower the risk of VR sickness for the player. Some base rules to follow and they will be updated as research in this topic moves forward.

Frames Per Second
Stay at the refresh rate of the display and don't drop frames or lag behind.

Always be tracking
The view should always track the user's movements. When the game is loading, in menus, paused or whatever the player should still be able to look around. No exceptions. No involuntary motions so do not add any head bob or camera shakes.

- Best visibility is the center one-third of the display.
- No scrolling text that the player have to read.
- Do not put a HUD on the player camera.
- Holographic interfaces

The input in VR is from the HMD's orientation and from the movement of any hand held input devices.

Stationary vs. Room Scale VR

VR Movement 
- Teleportion with quick fade.
- Avoid acceleration (increasing/decreasing). Use constant speed for moves.

Subpages (1): HMD