How developers are trying to solve motion sickness in video games

In an industry banking on the draw of realistic visuals and dizzingly-paced action sequences, motion sickness is not uncommon. How serious of an issue it is varies from game to game and player to player, but some developers are doing everything in their power to make sure it's not a problem on their own table.

During E3 earlier this year I played Techland's Dying Light, the studio's new free-running zombie IP that crosses the mad-dash parkouring of DICE's Mirror's Edge with the current zombie apocalypse trend. In the game, players take on the role of a young man tasked with doing supply runs and setting up security around a walled-off city populated by a handful of human survivors and massive hordes of infected undead. I enjoyed the way Dying Light strives to make players really consider their mortality under such circumstances and how Techland has managed to create enemies that are not only challenging and threatening, but genuinely horrifying.

In June, I was able to breeze through the game's 30-minute demo without incident. As someone prone to light motion sickness, I was worried that the game's jarring first-person visuals would affect me. It did not, so when I got the chance to play a new section of the game at Gamescom this summer, I was unconcerned.

After spending fifteen minutes running wildly through back allies away from a group of zombies, I became seriously ill. I reached out to Techland after the event to ask if the studio had made any significant changes to the game's head bob or tracking systems, anything that would have tampered with my proprioception.

We detect motion through signals coming from the inner ear, eyes and sensory nerve endings, or proprioceptors. Throwing one of these points off-kilter and out of sync with the other two will confuse the brain into thinking the body is poisoned and needs detoxification. This brings on the dizziness, cold sweat and sometimes vomiting.

Dying Light, like the oft-compared to Mirror's Edge before it, messes with players proprioception, or the way you sense your own body. Proprioception is the balancing act that our brain carries out so we know where our limbs are at all times and can use them without looking at them, like while climbing stairs or exercising. Most first person shooters don't tend to involve an on-screen character's body past what's holding onto a gun or other weapon, but in the case of Dying Light and Mirror's Edge, the emphasis on moving quickly results in some uncomfortable visual whiplash.

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But the hyper-awareness and depiction of a virtual body — in both titles, players can see their own hands and limbs if they look down at the right angle – could be detrimental in the long run to players without constitutions made of steel. It's why players got sick playing Mirror's Edge, and it's why I got familiar with a Koelnmesse restroom after playing Dying Light.

Techland told me that the studio is aware of Dying Light's ties to motion sickness and as development continues, the issue is one they are periodically testing for. According to programmer Bartosz Kulon and animator Kamil Franosik — whose responsibility it is to make player movement look and feel natural — the studio is constantly QA testing the title and making adjustments to avoid a queasy audience.

"We've checked the camera movement but also we compared field of view, the saturation of colors and changing perspective..."

"We actually don't remember when it first occurred, but after we received the first alerts concerning these complications, we undertook extensive research into the processes going on in a person's brain while sensing movement," Kulon told me. "After the theoretical research we made, we wanted to compare Dying Light to other games which include similar mechanisms and some other related content. We've checked the camera movement but also we compared field of view, the saturation of colors and changing perspective — mostly the parallel lines of the buildings and architectural order in general."

A handful of new gaming experiences coming out next year are offering new spins on the first-person view; some add parkour and zombies, other giant mechs and the ability to free-run up walls. After playing Titanfall for the first time at PAX Prime, I was happily surprised to walk away from Respawn Entertainment's booth without a trace of dizziness. Game designer Justin Hendry told me Respawn didn't "do anything special" to mitigate inducing motion sickness, but the studio's focus on making action flow seamlessly brought along a natural solution.

"We were more worried about the complexity of our motion model than we were about people getting sick from playing," Hendry said. "We wanted everything you can do to feel seamless and natural. From wall running, to wall jumping, to double jumping, sprinting, etc. A lot of shooters require you to play through their levels the same way every time, due to the fact that you can't really get around vertically. You constantly run through the same 'maze' the same way. If maps have too many 90 degree turns in enclosed spaces, that can cause motion sickness. So can spinning the camera too quickly while trying to target an enemy.

"In Titanfall, you can completely control how you want to travel through spaces, so you can skip tight corridors and just jump up to the top of the building instead," he added. "You aren't forced through anything and I think this freedom lets you keep yourself out of places that might make you uncomfortable, motion wise. Basically, we never force you through spaces that could make you motion sick. Every person can tolerate a different degree of motion sickness."

"Every person can tolerate a different degree of motion sickness."

But unlike Titanfall, Dying Light is all about the tightly-packed buildings and narrow alleyways. Among the long list of games Techland studied to figure out where they were going wrong with their design were Battlefield 3, Crysis 3 and Far Cry 3, as well as obvious choice Mirror's Edge and Splash Damage's first-person shooter Brink.

"It would be easier to say what we did not look into," Franosik said of Techland's research. Additionally, Techland turned to Youtube's wealth of personal parkour videos, many of them shot with GoPro cameras from just the angle the studio was trying to emulate for Dying Light. These videos helped them determine natural vision angles and head movement for the game. The team couldn't emphasize to me enough how much research was conducted into the issue, with developers picking into everything from how perspective shifts when certain sized obstacles are scaled to how many milliseconds it takes to swing the camera around and look at another object.

"Of course, you can't really go one to one, you can't directly move the whole process from these videos into (how the game works), but it helped us to get the right feeling of what it should feel like," Techland designer Maciej Binkowski told Polygon of the company's YouTube crawl. "[The research] was really about finding small things, because you know, Battlefield 3 is not really about the frame of movement, but they have particular animations when you go over certain obstacles that we also wanted to make. We should know how everybody else does it."

Techland's testing turned up some factors not directly tied to development, such as how close players are sitting to the screen and poor illumination in players' surrounding environment, such as dim lightning or too bright of a television screen. But others, such as weapons swinging faster than players are running, are in Techland's control. The studio found that one of its major problems was a jerky camera track, which would dramatically swing players' field of vision up and down when scaling or climbing objects.

"Your brain feels uncomfortable when you see certain movements on camera, but your inner ear doesn't get the signal."

"The problem with cameras in games like Dying Light is your brain feels uncomfortable when you see certain movements on camera, but your inner ear doesn't get the signal," Binkowski explained. "Normally in the world you get two signals: you feel the change in your body and then you see why the change happens, and then you feel okay. So in games you see that something is changing but your body doesn't really know why. That's where the discomfort comes in. Sometimes it's not only about the move itself, but rather how intense this move is, especially when you perform jumps and the camera rolls and sometimes the movement is too fast."

Binkowski said Techland viewed each motion available to players in slow motion to pinpoint where camera movement was not quite right. They combed through each move frame by frame and identified the moments in which the point of view's movement was too dramatic. Techland then had to tweak the camera track during these movements without pulling them too far away from realistic moves.

Something else Techland discovered that DICE learned long ago with Mirror's Edge is that a central focal point could mean the difference between illness and normalcy. DICE placed a tiny dot in the center of the screen for its game, giving players one point to focus on while moving protagonist Faith through each parkour obstacle course. Techland has done the same for Dying Light, Binkowski said, and added a small dot to the center of the screen to help players maintain balance.

This dot in the center of the screen was inspired by Mirror's Edge; the tiny point helped players focus their eyes and maintain balance among their senses while free running in first person view. DICE also removed head bob from the game after reports of players feeling ill. Both solutions were implemented after the developer spoke with ballerinas to determine how they could complete long series of spins without feeling dizzy or sick.

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"Problems with motion sickness appear when pretty much everything moves and everything is blurry," Binkowski explained. "Like when you sit in a car and you start getting motion sickness you can actually look up and far away because those points on the horizon will move slightly or not at all. These give you more comfort. We added this little dot in the center of the screen so even when the whole world is shaking and turning there's a point that when you look at it, it's always in the same spot."

After Gamescom, Binkowski said the team analyzed the demo against the E3 slice, which is how they discovered the issue with the camera track. Movements were completed at the same speed in both demos, such as climbing the side of a building, but were done so at shaper angles in the Gamescom demo. The Gamescom demo's camera had a "bigger acceleration stroke," Binkowski said — a fancy word for head bob.

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The problem with creating a first person hack and slash, Techland's designers said, it that unlike a first-person shooter there is no visual reference on screen when you attack an enemy. In your typical FPS, this is usually the gun you're carrying. A hack and slash comes with a hefty amount of arm swinging and a weapon that flies all over the screen while the character is still moving. Placing a dot in the middle of the screen can mitigate the problem, but won't necessarily solve it for all gamers.

"This is definitely a serious issue for us," Binkowski said. "We want players to feel comfortable playing our game, we don't want to stress our players. It seems like a small number of people are affected by it, but it's really something we want to get right.

"But there is no recipe that says if you put a dot in the middle of the screen and do this and this, it's gonna go away," he added. "We know all those things and we try our best and we think we're getting better and better at eliminating the feeling. It's not something that we can say we're done with yet, we're still working on it and finding new stuff and going over all the animations. There's still stuff to do, but we're close."

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