Comfort is an entirely new field of user experience that is emerging in VR. Does it have a formal definition yet? Here's mine:
VR Comfort refers to the degradation or enhancement of your experience that reduces or eliminates nausea or uncomfortable feelings.
There are two main ways to do this:
- Options. Give your users some things to change in the options menu to improve their comfort.
- Controls. Add alternate ways to move around or interact so that players can determine which play style is most comfortable for them.
Ok so what are these 10 things that you should think about? If you're like me, you probably skipped down to the bold text- so let's get into it.
1. DO Offer a Blink Mode
If your game or experience has the player moving around in some way beyond the bounds of their current local environment, offering a blink mode is a great way to let players degrade the experience to their own comfort level. What do we mean by blink mode? Essentially it is the elimination of camera movement animation- teleporting the player instantly from one place to another. In tests we've done, we've found that players will not become sick from instant movement. Remember- we have to unlearn a lot of what we've learned with PC game design and consider this new medium. There are some things that won't be readily intuitive to game developers- and having a blink mode is one of them. How can you implement a blink mode? Either put it in the menu of options- or offer it as an alternate control scheme on the controller or keyboard. You could also have a button that toggles blink mode on or off. Or you could do what Cloudhead games does and make it a core part of the gameplay. Check out this video:
2. DON'T Stick a UI on the Player's Face
This has become a best practice that I've seen a number of other developers talk about. Sticking a UI to the player camera creates a very uncomfortable experience for some reason. This probably has to do with the fact that we have no such parallel in the real world. The job of the interface designer is about to get a lot more complicated as we scramble to find ways to show the interface that are anchored to the virtual world in some way. How do persistent displays in VR work? Health? Ammo? Alerts and alarms? All of these need to be thought about carefully when you're building your game. Holographic interfaces within VR seem like a natural fit for this problem. Make the interface transparent and affix it to something in the virtual space and you'll eliminate many of these problems. Have a look at how Tilt Brush handles UI:
3. DO Give players the option to turn on Transparent Skybox Reference Points
A company called Triangular Pixels had a novel way to improve comfort through 'Magic Stability Cubes.' These semi-transparent cubes are placed throughout the skybox and give the player a reference point when there is movement. It would be nice if more games created this kind of option and tucked it away in the comfort options so that players who are more prone to nausea can still experience the game. Have a look:
4. DON'T Move the Player When They Don't Ask you to
Simulator Sickness is a very real thing that was discovered by the US military in the 50's when soldiers tested simulation devices and didn't have the corresponding inner ear movement associated with what they were seeing. There are a lot of things that can cause simulator sickness, but most of the data that's out there seems to point to it being caused by a discrepancy between what your eyes are seeing and what your body is feeling. Player movement in VR needs to be predictable and player triggered. If a player is standing around and is suddenly moved by the game to some other location- that's going to increase the likelihood of simulator sickness. Come up with clever ways to move the player that are actually triggered by the player.
5. DO Allow Snap Turning
Even though they're not possible in the real world, we've found that snap turns are a fairly comfortable way to turn in VR. Instead of animating the world rotating to the next viewpoint, the player is rotated instantly (or nearly instantly). It's tempting to feel like this may degrade the player's enjoyment of your game, but remember that a comfortable experience should be the highest priority. Making something like snap turning optional or relegated to buttons on the controller is a great way to give the option to those who want it. Cloudhead Games has a great example video that shows what snap turning looks like:
6. DON'T Force Over the Shoulder Interaction
This advice applies to seated experiences only: Putting essential information over the player's shoulders will greatly decrease comfort- and may actually injure some players who have had neck injuries. Sure, it's fun to put things behind the player, but leave that to non-critical info, or give the player a way to turn around such as snap turns.
7. DO Build for High Performance (And Avoid Judder)
What is "Judder?"Judder is a term that used to only describe a noticeably lower frame rate. It has become commonplace in a VR context to describe the stuttering feeling that happens when the head motion is faster than the computer can render the environment. This feeling is very uncomfortable, breaks immersion, and can even make players feel sick. How to reduce or eliminate judder? Optimization. All of your geometry, textures, programming and animations need to be optimized as much as possible so that there is as little strain on the CPU/GPU as possible. Build and test for low end machines, and attempt workarounds that reduce the complexity of your scenes without sacrificing graphical quality.
8. DON'T Accelerate the player
Acceleration has a nasty tendency to cause simulator sickness. The inner ear expects movement to occur but the body doesn't feel it. This discrepancy between what the eyes see and what the body feels causes the body to feel as though it's being poisoned- which will result in nausea. To work around this problem- test movement that pushes the player forward instantly at a steady rate. There is still much work to be done in this area as far as testing goes- and I wouldn't be surprised if some enterprising developer figures out a way to accelerate a player without making them get sick- but for the time being, try to avoid it whenever possible.
9. DO Put Objects Near the Player
It turns out that having objects near the player provides a point of reference that can greatly reduce nausea. In fact, some researchers have found that putting a digital nose into their VR experience caused a noticeable difference in how long players could play their game. Check out this overview:
10. DON'T Cause Conflicts Between the Player's Body and Their Avatar
It's been said anecdotally that it is actually more comfortable to look down and see no body than to have something strange going on with a virtual body (such as a body that is doing things you're not). The ideal scenario, of course, is to have a body that corresponds to the player's body 1 to 1. But in the absence of that, no body at all may be the most comfortable option.
Bonus: DO Avoid Claustrophobic Environments
Many people deal with real issues like claustrophobia. Try to avoid putting players in that kind of situation unless your game is specific to a genre that encourages discomfort (such as horror). Give your player lots of room to move and look around. Tight spaces could be good from a storytelling standpoint if there is a need to increase tension- but don't leave the player there for too long. Give them a way to get out as fast as possible or at least make the exits clearly visible.
We've still got a long way to go, and Block Interval is hard at work solving these problems for our own games. Hopefully this list has gotten you thinking of ways that you can reduce nausea and improve comfort in your games! See you in the other world.