Whether you're developing your first game in Unity as a hobby or are a seasoned game developer at a large gaming company, you have a difficult job ahead of you.
Your game has to have a clear direction, be visually appealing, technically immaculate, have just the right amount of difficulty in its design levels to appeal but not create a cognitive load for the player, and it has to please an audiance.
And that is just for a 2d game. Now going in to a 3d or a VR game, you have to consider emobiment, battling the feeling of neausia which will repell people from playing your game and creating immersive environments that work with the physics and the limitations of the controls and the tracing options that are available. Tough job! So here are a few tips from neuroscience that can help you overcome some obstacles independently of you're creating a game for a master like HTC Vive or a smaller arena such as your avarage smartphone. Some if not all may seem obvious, but very few use these tricks in the current state of VR.
1) Render an avatar-body.
As a former researcher at Karolinska Institutet I would frequently participate in studies as a test subject. I have been electrocuted, poked, pumped full of hormones and stabbed. The ladder was the most fun experience and the very thing that made me interested in VR. The experiment in which I was stabbed was at Henrik Ehrsson's lab. More about the experiment here. To make a long story short, through a VR headset, the researchers were able to trick the participants in to thinking they had switched bodies with a manaquin / or been made invisible. at which point the researchers stabs the "avatar body" to register pain in the test subject. They saw that for a second the brain sends pain signal to the "host" body. Your body reacts to the pain of the manaquin.
This study is important because to immerse yourself you need a worldly connection, which is your body. Only seeing a pair of hands, does a bit for the immersion but not as much as seeing a whole body, thus creating the same embodiment-effect as shown by the Ehrsson lab studies. Even though there aren't any tactile cues yet, when our own bodies equipped with haptic feedback vests, we will be able to feel more connected to the avatar body and enhance our experiences of being in the game.
- I myself experience the difference while playing games which render and do not render a body. The perfect example is the game KITCHEN.. I experienced the same pain illusion as I did during the experiment.
2) Create organic movement, skip the motorcycles and spaceships - go by car.
This article sums up pretty well which factors influence nausea in VR. Some of those can be avoided, but some, such as the finding that Neuroticism is involved in the susceptibility to nausea, are harder to change.
So how does one get around it? Well in tip nr 3, Mats Millberg will tell us how to minimize the nausea through better tracking but there is another way to get around the problem.
Reduce the need for movement. There are two organic ways to do things in VR currently. Stand and sit. Until the day we have an TMS EEG VR, perhaps we should adapt the experience to the brain not the opposite.
PSVR is an excellent example of bad tracking. Studies which have been preformed show that creating a more organic way to move decreases the risk of nausea, even with less than optimal tracking. LÄNK
Example: PSVR (with horrible tracking) has a good game - VR Worlds - London Heist.
You rarely walk to your destination. You either sit and have conversations, or are transported in a car. Both things you're brain is adapted to doing in real life. Riding on something rather than standing and walking, is a simple way to trick the vestibular system. The reason why spaceships and motorcycles still make you nautious is due to the fact that your visual input still needs a frame of reference, and a spaceship that goes up and down, would make your neausiated outside of VR as well!
3) Tracking - interview with Mats Millberg
What role does tracking and frame rate have in experiencing nausea in VR?
I believe position tracking and low frame rates are the main reasons of nausea in VR. The brain doesn't like being confused, it treats the disconnect as a poison because it is unnatural for the brain.
I think frame rates are a problem when they drop below 75 fps. Tracking issues do mainly occur on more basic VR systems like PSVR which has less sensors than high-end systems like the HTC Vive.
What can developers do to deal with the problem of bad tracking in e.g. PSVR?
- Even though I personally get the feeling that a lot of PSVR-tiles have too low frame rates I also know that PSVR-titles are forced to have a fairly high frame rate of at least 60 fps (reprojected to 120hz). So the bad frame rate problem is more common on other platforms were consumers have low performance hardware. One solution could simply be to refuse to start the software if fps detection is too low. I would also suggest spending some time on optimising everything to make sure it runs on hardware with as low specs at possible.
Regarding the tracking problem of headset and controllers I believe the best way to get as good tracking as possible is to really think about how headsets and controllers are being used. Since tracking on PSVR is only preformed from one direction (forward-facing Playstation-camera) it`s really hard to get good tracking of both headset and controllers at the same time. If you hold the controllers in front of you they often block the view for the camera, so it's unable to track the headset. Or if you face the other way from the camera it can`t even see the controllers behind you which makes tracking impossible. I think the best VR experiences on PSVR are those which don't require tracking of the controllers, so that the tracking being made can be focused on the headset only. But if you really need controllers on a system like PSVR I would probably build the experience so that the user never has to turn all the way around and I would really consider the placement of the controllers.
On other systems such as the HTC Vive and Oculus Rift, the tracking is almost as good as it gets because of the use of multiple sensors. Focus here should be on optimising performance and really think about the placement of the headset relative to controllers etc.
4) Follow the Reality of Virtual Reality
This one is simple. How often do you walk though objects in real life? Sure, breaking the laws of physics has its charms, but do so consistently. If there is a wall, it should not be penetrable unless the laws of the universe it is in has rules that permits it. Small things, such as transferring simple laws of physics or breaking them while creating a set of consistent predictable rules, increases the chances of full immersion.