Loco-motion: The ridiculous state of VR movement

When I first heard about the Oculus Rift, I was excited to see how it would revolutionize gaming. Then, when the Vive was announced and introduced room-scale VR and tracked controllers, I was even more hyped. However, while looking down the sights of a gun in Raw Data or throwing knives by flicking my wrist in Budget Cuts was impressively engaging, I felt that many VR titles were, in a way, a regression from the overall gaming industry. I couldn’t find any games that made me feel nimble and acrobatic like Mirror’s Edge or Titanfall. There were no games that allowed me to walk slowly so that I could immerse myself in vast environments like in The Elder Scrolls IV: Oblivion. Instead, I was stuck in a 2x3 meter rectangle pointing and teleporting to get around small game worlds. I didn’t feel like a powerful hero immersed in a colossal world; I felt like a bound prisoner trapped in a tiny cell.

Teleportation, in particular, is a big reason why I’m disappointed in the current state of locomotion in VR. Besides feeling limiting and unfun, it is also the main form of movement in many rooms scale VR games. Part of this could be because Valve itself used teleportation as the main form of movement in The Lab, a launch title for the Vive meant to show off VR. While teleportation is simple to use and nausea-friendly, it feels out of place in many games, almost like an afterthought.

VRemedy Labs, the company I helped to found, has been working hard to change this. Our team is composed of engineers from MIT, passionate about the future of gaming and virtual reality. We are tackling the problem of fun, empowering locomotion in VR that doesn’t cause motion sickness or nausea. Addressing nausea is key to achieving interesting movement mechanics, because it is part of the reason “safe” (aka lame) mechanics like teleportation are used.

Below I will discuss some of the movement systems we’ve experimented with, noting their advantages and disadvantages compared to teleportation (the movement system most encountered in VR games).

Boosted movement

Our idea for this movement mechanic was to experiment with room-scale movement tracking that wasn’t 1:1. Instead of walking 1 meter in real life equating to walking 1 meter in game, player movement is amplified so that 1 meter in real life is 5, 10, or even 100 meters in game.

We liked that this form of movement kept the smooth, immersive feeling of walking that is absent in the teleportation mechanic used by many VR games. Users could switch between three levels of amplification based on the number of triggers held on the Vive controller (0, 1, or 2), allowing players to explore both large and small spaces in game. When we playtested this mechanic, we noticed that players who could handle normal room scale VR movement were also able to handle boosted movement without getting nauseous. We also noticed that playtesters very easily got accustomed to the speed of boosted movement, so much so that returning to the reality of 1:1 movement felt slow to them afterwards.

While we do prefer this type of movement over standard teleportation and joystick movement, the scale of the room still restricts the user’s freedom. Rather than being stuck in a 2x3 meter space, you are stuck in a 20x30 meter one. Boosted movement obviously improves immersion, but users run into the same problem of reaching the boundary of your physical space as found in teleportation.

Tractor Beam guns

This form of movement was a little involved in comparison to boosted movement. Users had two different “guns” in each hand, one that pulled them towards objects, and another that pushed them away.

What stood out most about this type of movement was the “cool” factor. Testers particularly enjoyed the ability to scale large environments using their dexterity and aim. Fun mechanics emerged from this type of movement, like using the pull gun as a way to “grapple” onto walls and ceilings. Compared to teleporting and boosted movement, this system afforded very large and spread out level layouts, which are rarely seen in VR games that use teleportation. At first glance, some might say that this type of movement is too specific and would only work thematically in certain types of games. However, we argue the same could be said of teleportation. Adjustments could be made to make this movement suitable for games that require more restrictive movement, such as by not allowing the push and pull guns to change the player’s vertical position.

As a note of caution, we found that testers managed interpret the use of the mechanic in diverse ways. Some would elevate themselves with the push gun while steering with the pull gun; testers who gravitated towards this use found themselves very free and unrestricted. Other use cases included attempting to use the pull gun as a grappling hook while steadying themselves with the push gun. These testers seemed to move around the environment as though they were playing a platformer.

Space Fabric movement

We came up with something a little more abstract for this type of movement. In a zero gravity environment, players could “grab” at the air (which we referred to as “space fabric”) and propel themselves in the opposite direction that they pulled this “space fabric.” For example, to move forwards players had to hold the Vive controllers in front of them, hold down the grip buttons, pull their hands back while still holding the grip buttons, then let go of the grips.

The most notable thing about this mechanic was how easily playtesters were able to pick it up and nimbly maneuver around the environment. We were able to give them verbal instructions while they had a headset on that gave them enough information to figure out how to use this movement system. Some testers mentioned that the movement felt similar to swimming. The benefit of this movement system is that it isn’t affected by room size at all. Players only need to turn and “swim” with their arms. We gave the player character standard pistols in each hand in our prototype as well, and testers were still able to locomote and shoot with ease.

Iron Man movement

This is the movement system we chose to make a prototype game around to further examine how intense locomotion could work in actual VR games. As you can guess from the name, the Vive controllers acted as thrusters you could hold in your hands. Pointing your thrusters towards the ground would launch you into the air, and pointing them behind you would allow you to fly forwards.

Out of all the movement systems we tested, this is the one that most testers spent the longest time in, and found the most extraordinary. The demo environment we had testers in consisted of a small forest, which testers enjoyed weaving through as they were flying. Players were able to grasp the mechanic quickly, and enjoyed the feeling of mastering flight in the demo environment.

We designed a Mario Kart-like battle racing game, Robo Rocket Racer, around the Iron Man style movement system. Players were able to race around a large island, avoiding obstacles and collecting powerups to use against enemy AI racers. A lot of our time was spent tweaking our movement to feel fast, fun, and rewarding. We ended up very happy with our end product, but realized there was a big obstacle preventing our movement system from being completely practical.

Nausea in VR

In some of our experimental motion mechanics, especially the Iron man movement used in Robo Rocket Racer, nausea became a prominent issue. Flying through boost rings, rings that would accelerate the player if they flew through them, was a problem for a few testers; some would get dizzy and disoriented, and others would need to take the headset off immediately. After some gameplay, most players were able to handle the flying just fine, but getting even 5 minutes of gameplay in is difficult for gamers who get motion sick easily.

Avoiding nausea is one of the main reasons movement mechanics like teleportation have become so prominent. No change in velocity occurs, and as a result there is no mismatch between what the player’s visual system sees and what their body feels, so they tend not to get motion sick. But limiting VR movement to make playing VR games bearable seems to be an unfair trade off. Putting on a VR headset and being transported to another world should feel empowering, not restrictive.

Key Takeaways

The key takeaways from our experiments with alternative motion mechanics are:

  • Teleportation is safe and nausea friendly, but hurts immersion and limits gameplay potential. There is no room for mastery and skill in teleportation

  • Other motion mechanics, such as the ones we described, present the opportunity for more skillful locomotion is varied environments

  • Nausea is a limiting factor for movement mechanics, but it can be worked around. Gamers shouldn’t settle for less fun forms of movement; Developers should design their locomotion systems to be more nausea friendly

Currently, VRemedy Labs is working on I Hate Heroes, a VR game that lets players live out their childhood superhero fantasies without worrying about nausea. Our proprietary comfort acclimation system, developed at MIT, allows even the most nausea prone players to swing, fly, and more! Check out https://vremedylabs.com/blog for updates on our work.