Shared Rooms: Designing Multiplayer VR

The future if virtual reality lies in connected, multiplayer experiences. Thanks to the relative youth of VR as a medium, these also happen to be themost challenging to develop. New tech means a new set of problems and constraints to overcome, but also the potential for completely unique social applications and competitive games.

Developers agree that with real-life physical movements mirrored in VR thanks to motion controls comes the new sensation of ‘social presence’. The feeling of sharing a space with other players that transcends even the most immersive MMO or online shooter.

Physically interacting with real people in a shared world has the potential to rewrite the rulebook, even at this early point in the technology’s lifespan.

David Votypka, senior creative director at Star Trek Bridge Crew dev Red Storm, foresees this as being a key selling point for virtual reality as the technology progresses.

“There is a growing consensus that social VR is going to be one of the tech’s most powerful uses and most influential aspects,” he explains.

“I’ve been in that camp for almost two years now, because VR can literally make people feel like they are in an environment with each other as opposed to simply viewing each other’s avatars, known as social presence or shared presence.

“As technology advances and as we get more data from VR hardware to represent users more accurately in the VR environment, the more powerful and compelling social VR will become.”

Piers Jackson, game director at RIGS: Mechanized Combat League Developer Guerrilla Cambridge, feels that this idea of shared presence is just the start: “The first waves of VR titles will largely focus on delivering on presence and experience. But going forward, player-to-player interaction is going to become more prevalent simply because when it works, it’s magical.”

Player-to-player interaction is going to become more prevalent in VR simply because when it works, it’s magical.

Piers Jackson 

BRINGING PEOPLE TOGETHER

But it’s the technical constraints that currently limit person-to-person interaction, a by-product of the newness of the hardware, that are also the most troublesome part of developing multiplayer experiences in VR. Top of the list is mapping the player’s physical movements onto their in-game avatar.

Votypka believes that social presence “occurs because our brains can immediately detect the difference between watching an animated avatar move and act, versus one that reflects actual and real human motion”.

So far VR devices are only using head and hand tracking to replicate player motion in their digital worlds, which makes it difficult to fully recreate complex movement using the human body’s full range of limbs, joints and appendages.

“If we start thinking about multiplayer VR games that feature full body avatars, freeform locomotion, the ability to manipulate objects, and to also interact with other avatars by way of combat or handing off objects to one another, the level of complexity increases quite a bit,” Votypka tells us.

“Overcoming these challenges requires approaching each of the aforementioned features with solutions that involve adapting previous techniques in new ways and, in many cases, it may very well require a solution that hasn’t been done before.”

Developers are working hard on coming up with solutions for these problems but, in the meantime, some are choosing to present players to each other as nothing more than a floating head and hands.

“That’s obviously not the ideal solution,” says Lauren Bruins, co-founder of Arizona Sunshine developer Jaywalkers Interactive. “We’re still investigating how we can show a full player character without it looking weird.

“We’ve built a special IK-rig for the character and try to mimic the player movement as close as possible. A lot of guesswork is needed there, because we only know the positions of the headset and the hands, so we try to keep its movement within bounds that make sense.”

Guerrilla Cambridge has a similar solution, even though the mech combat setting for its game makes things easier on the team. “We wanted players to have full immersion in the game and so our pilots have full body representations,” Jackson says. ”Their hands are positioned where the player’s hands are likely to be and we also track the player’s head position and use IK to move the shoulders to compensate.

“Having said all that, we did spend a lot of time getting the pilot’s position to work and finding a solution that suits most people. Having a male/ female avatar switch certainly helps.

“Equally, when the disjoint is too great it feels odd and breaks presence so I think the floating hands solution is a smart one for some games. Perhaps this is a route we might have gone down if we hadn’t effectively dodged many of the problems by having the Rig do all of the motion for the player.”

Multiplayer for VR will create completely new experiences that could help drive adoption.

Clemens Wangerin 

ELBOW GREASE

Votypka details the true extent of the issue: “The challenge specifically with arms is that developers have no way to reliably establish where the elbows of the player actually are. For example, we have no way to determine the difference between a wrist rotation with no elbow movement, versus an up or down elbow movement that consequently rotates the wrist.

“The format of Star Trek Bridge Crew also really works for us since it is a seated experience and the interaction space for the player is generally focused on the panel in front of them. This reduces the problem set we have to deal with.

“While there will be instances, where the player’s real-world arms won’t precisely align with their in-game arms, the differences are minute enough and infrequent enough that we have less disconnect than we would if we used floating hands.

“We’ve had hundreds of players try [Star Trek Bridge Crew] so far, and when they actually get to see their arms move in the game, the feedback has been really great; there’s no question that it greatly adds to their sense of presence.”

But thankfully, at least in the short term, exact one-to-one mapping isn’t completely necessary because the human brain does a good job of filling in the blanks.

Also, as Bruins explains: “Other players don’t know the exact way players are standing in their room, so there is some leeway. I think we’re on the right track, but I definitely can’t say we’ve overcome the challenge completely.” Votypka adds: “It seems more and more likely that the next generation of VR hardware will provide developers with greater body data to utilise. For example, arm and elbow positions or camera-based body tracking, as well as tracking eye positions and even facial expressions.”

Other players don’t know the exact way players are standing in their room, so there issome leeway.

Laurens Bruins 

SHOW YOUR MOVES

Another problem facing Virtual Reality involves player movement – buzzworded as “locomotion”, because long words are cool. “Moving in VR, other than movement you do yourself, is not a pleasant experience for many people – yet,” Bruins explains. “Because of this, most games use teleportation, as do we, which is strange in multiplayer if you see everyone teleporting around. We’ve investigated a few solutions and think we’re on the right track.”

One way of combatting this is limiting the player to an exclusively seated experience. Clemens Wangerin, MD of VTime Limited, which develops online virtual reality social experiences, says: “Creatively almost anything is possible, but we find that movement or locomotion of the user needs to be handled with particular care. That’s one of the reasons we designed VTime as a seated experience and use movement sparsely. This results in a higher comfort factor and leads to more users spending more time in your title.”

Seated experiences also “almost completely bypasses risks for motion sickness in VR”, according to Votypka. “But locomotion is a solvable problem and it is being solved by advances in both hardware and software,” he says. “In the worst case scenario, people who are very sensitive to movement in VR can use teleportation mechanics.”

In an ideal world, everyone will be taking advantage of large virtual reality play spaces, making full use of the format’s room scale features. Jackson sees the issue of space, as well as human laziness, as being limiting factors when it comes to fully physical multiplayer environments.

“I’d like to think that a physical motion approach to multiplayer games is achievable,” he says. “But I suspect it will need to overcome the issues of available space and will have to create a level of engagement that provides an experience which is totally original – because, unfortunately, a sedentary experience sat on your sofa at home is frankly more convenient for most people.”

Votypka believes these issues are all just teething problems and that “additional mechanics are being developed and discovered that mitigate discomfort from moving in virtual reality”.

“Because there is a very wide range for how people react to motion in VR, I believe that one of the keys from a design perspective is to build games with locomotion schemes that allow users to customise them according to their level of sensitivity,” he suggests.

“Also, it’s been proven that for many people the more they use virtual reality, the more desensitised they become to motion sickness, which is another reason that users should be able to change the locomotion settings in a game as their sensitivity changes over time and use.”

Once developers come to grips with this new medium and a set of best practices begins to emerge, the consensus is that multiplayer will be the key to mainstream adoption of virtual reality. “Multiplayer ‘designed for VR’, and in particular anything with persistency to it has significant scope to break new ground and create completely new types of experiences that could help drive adoption,” says Wangerin.

Bruins agrees: “Multiplayer VR games that have clear representations of other players might be even more social than traditional multiplayer games, because player movement directly translates to the player’s avatar. Movement and emotions can be very clearly conveyed, which was actually quite surprising when we first tried it out. I definitely think multiplayer will play a major role in the adoption of VR.”