How can we Prevent VR Sickness with Level Design?

Hello there! It’s me again.

I’d like to share with you a few things about VR sickness we discovered as we were experimenting with FATED. We already broached this topic in the technical posts, but today, instead of talking about technology again, we’re going to talk about how to avoid this unwanted feeling from a design point of view.

As we were looking for the cause of the sickness, we found that it was mainly caused by the inner ear and the eye sending different messages to the brain at the same time. When the player is moving in Virtual Reality, the eyes inform the brain of the movement, but the inner ear, an authority on the subject, says otherwise. This is where the dizziness starts. Some actions have a greater effect than others, so by strategically choosing which actions to ask the player to perform, you can diminish the undesired effects. Some of these actions can be easily identified, including: height variations, rapid movements, acceleration and deceleration, rotation, and unprovoked movements.
By following a few basic rules, your level design can make a big difference on your game’s level of comfort.

Avoid making height variations in the environment.

Making the environment flatter will keep the player’s eye at the same height. This will also keep his inner ear stabilized, thus no weird feeling. This doesn’t mean that your environment should be totally flat, only that the part where the player is allowed to go should be “flatter”. After some testing, we also found out that a floor angle of about 10 degrees is still comfortable for the player. If you have a slope with a greater incline, a feeling of vertigo might start to set in, but this could differ from one person to another. So try to avoid making a VR game about running up and down flights of stairs. If you can choose between stairs and an elevator, go with the elevator. Also, downward vertical movements seem to be easier for the brain to handle. This is why roller coasters are so effective at creating a powerful feeling of vertigo and nausea.

Avoid making rapid movements.

When tweaking your character’s speed metric, consider a real-life scale speed instead of a fictitious one, to make the brain adapt more easily. Also, if you have elements like a moving platform or an open elevator, keep their movement slow.

Avoid acceleration and deceleration.

It is better to set a constant speed that will be achieved in one frame instead of accelerating over time. Stopping should also happen instantly. This works well with speeds that are not too high. But I can’t say for very high speeds, as I haven’t experimented with those kinds of parameters.

Don’t ask your player to rotate too much.

Try to avoid having the player make repetitive rotations. Completely avoid 180-degree rotations in you walkthrough if possible. Try to present the player’s options and interactions in front of him or in a narrow angle of perception. I don’t mean that all the game should be played in a corridor; this would be bad and boring. We didn’t make FATED like this. This is more about keeping in mind to avoid repetitive rotations than not making any.

Completely avoid unprovoked movements.

By “unprovoked movement”, I mean any movement that is not triggered by the player’s input. So, no surprise elevator, no sudden floor rotation, and, above all, do not take control of the player’s point of view like we see in so many first-person and third-person cut scenes.

These few simple rules can help avoid VR sickness in your game. It is only a matter of approaching level design with that in mind. I saw some of the game’s design change radically from a first-person adventure to a fixed standing experience or third-person point of view. This says a lot. VR sickness exists, and we can’t ignore it. We have to find a way to create our game in a way that makes this undesired feeling as absent as possible. I may be wrong, but I don’t think that technology will be able to counter this effect, as it is triggered by our own perception system. Trying different conceptual approaches may be the best hope we have of finding a solution to the issue, and if we want Virtual Reality to rise as a new medium, we have to create “sickless” experiences for the masses to enjoy.

Thanks for reading! If you have comments on what you’ve read here, or if you have tips and tricks that can help with VR sickness, please share them with us!

Philippe Dionne / Game Designer
www.fatedgame.com