Based on the Google I/O talk, Reddit r/gamedesign discussion and my personal experience in working with VR, I decided to put together a thorough list of things to consider when designing for virtual reality. Hope you find it useful.
Simulator sickness can be reduced by placing a virtual nose in the center of the field of view. When fixed visual reference objects - such as a race car's dashboard or an airplane's cockpit - is placed within the user's field of view, the affliction can be eased.
Don’t cause motion sickness. We have been evolved to be very sensitive to vestibular ocular disparities. Thus, always maintain head tracking, never drop frames and keep a stable horizon.
In the real world, people can only feel acceleration, not constant velocity. That applies in VR as well. So leverage acceleration if you want the user to feel momentum.
Don’t prevent the user from taking control of the camera. The user must always be in control of where they’re looking using their head-mounted display’s head (rotational and positional) tracking.
If you want to integrate a narrative or storytelling into VR, get the user’s attention by providing visual cues that are often used in game design or even the real world. Or have the story progress dynamically based on where the player is actually looking.
Allow the user to experience by sitting down and walking.
Don’t allow the user to collide with object or go through an object.
Don’t stick large or overly-complex interface to the user’s face. It not only obstructs the user’s field of view, but it also make it difficult for the user to interact with the virtual environment. If HUD-like interface must be integrated, keep it glanceable.
Make the user feel at ease by placing them in a room that is not uncomfortably large or small.
Sense of scale in virtual reality should match the reality to make the experience more pleasant, unless it’s intentional.
Avoid sharp or dangerous objects, unless it’s intentional.
Overlaying a visual aid, or “reticle" makes targeting objects much easier. The reticles are unobtrusive and react to interactive elements in the environment.
Guide the user with subtle cues such as light or spot lights without creating obstructions in the environment.
Use gaze cues to encourage the user to interact with the environment.
When triggering audio or other events, consider leveraging the user’s position and field of view.
People don’t move their heads initially. If you want to encourage the user to see and interact with areas of the environment that is not shown initially, place objects (with cues) that the user can interact with near the peripheral vision.
Try out designs that leverage the whole canvas and surround the user.
Consider physiological and environmental discomfort such as agoraphobia and claustrophobia.
The form factor of HMD (i.e. Oculus Rift vs. Samsung Gear VR/Google Cardboard) will often dictate whether the experience will be more long-term or bite-sized.
Based on the type of lens in the HMD, the perspective and field of vision may need to be updated in the experience.