For all the freedom we imagine VR can provide, there's still a significant confining factor: the amount of real-life physical space around you. Here's how devs are tackling the issue of locomotion in VR.
The new generation of virtual reality technology promises freedom from your immediate surroundings, allowing you to explore digital worlds with a degree of fidelity never before possible.
But for all the freedom that we imagine VR can provide, there’s still a significant confining factor: the amount of real-life physical space around you. You can't just walk around your house with a headset on and experience a VR world, at least not yet. Devs have been left to figure out how to allow players to move greater distances within a VR space, lest players be limited to a single virtual room at a time.
This locomotion problem is one that was immediately recognized by game developers who are making certain types of room-scale VR games, particularly ones that require moving across distances greater than the size of one room.
The solution for many VR devs today is a teleportation mechanic; select a point off in the distance and reappear at that point. But there are many different approaches to that solution, and there are unique locomotion problems that developers had to solve depending on the needs of their respective games.
Developers of games including Budget Cuts, Bullet Train, Defense Grid 2 Enhanced VR Edition and others (not all games below are room-scale) each answered a few questions on how their games expand the virtual space via teleportation and other kinds of locomotion mechanics.
How teleportation works in Budget Cuts
In Budget Cuts, our long-range locomotion system comes from a device known as the translocator. You aim somewhere in the level, and fire a small beacon. When this beacon lands, it opens up a portal in your hand. This portal can be used to see where the beacon is located, as if you were standing there. When you press a button on the controller, the portal wraps around your body, and you are then standing at the new location.
Prototyping and iteration
We started out just doing straight-up teleportation by pointing and clicking, and immediately putting the player in the new location. While it works well and doesn't cause any motion sickness at all, it feels a bit jarring. There's no smooth transition at all, so we wanted to make it so. The portal just came naturally after that.
Why the final design
Having a portal gives you that smooth transition, without any nauseating movement, while also giving players a chance to see where they'll end up before they teleport.
On teleportation mechanic and room-scale VR
I think teleportation is one of those things that's not going away anytime soon. Accelerating players in VR is sickness-inducing, so there has to be movement without acceleration, or movement within room-scale. Anything else is going to make a certain portion of your playerbase feel sick playing your game, which is bad not only for your game, but also VR as a whole. There will be a lot of games designed like Job Simulator, where moving longer distances is simply not something you do, and games like our own, using teleportation.
How teleportation works in Bullet Train
Our teleportation mechanic works by having the player press a button, which activates your teleporter. We also put the world into slow motion at the same time, which gives the player a bit of time to think if the action is too hectic.
When the teleporter is active, a beam extends from your controller, which you can then point at specific locations around the level, or at the enemies themselves. When you release the button, you blink to the new location, complete with a sound effect, and a flash to white. We also add a trail effect leading back to where you came from to orient the player.
Prototyping and iteration
We arrived at teleportation after realizing that we desperately needed a way to move around the environment.
Our very first idea was to do something a bit like the Showdown demo, where you're moving through the scene at a constant rate, and enemies are running towards you. I had a prototype where you could steal a night stick off the enemies' belt as you passed by them, and beat them with it. It was pretty cool, but as soon as you passed the enemy, players had a tendency to turn around to hit or shoot them, and that would cause the motion controllers to lose tracking because the player’s body got in the way of the cameras. Doh!
That was one of our key constraints for the Bullet Train demo, so we had to try and keep the player facing in one direction as much as possible. I'd seen a few other games that were playing with teleportation, and I knew I wanted to give it a shot. To try and keep the player facing forward in real life, we set up the teleporter locations around the perimeter of the level, always facing inward, so that the player didn't need to turn around to shoot. The action was usually in the center of the map, so after the player teleported, they were automatically facing the action.
Why the final design
Our current design fulfilled the requirement of keeping the player facing forward for the most part. It was pretty easy to learn and the player didn't need to turn around most of the time, but it came with some trade-offs.
Re-orienting the player when they teleport can tend to be a little disorienting, particularly if you're not sure which way you're going to be facing when you arrive. Most people got it with a little practice, but we still need to do more work at communicating your destination orientation visually. Another downside is that there is a very limited amount of positions that you can teleport to because they all have to face the action.
I've done some prototypes with a more "free-range" teleportation style, but for the purposes of the Bullet Train demo, it was too much to learn in such a short (6 minute) session. For many people, this was their first time in VR, and we’re already throwing a lot at you! This prototype was a "aim where you want to go" style teleporter, which worked fairly well, but had one slightly unexpected downside compared to the fixed-teleported method: from normal hand-height, it's really hard to steadily aim at a point on the ground any more than a few meters away while orienting, because of the limitations of your wrist. Recently, I saw the Budget Cuts trailer (above), and I think the projectile aiming method could help alleviate that quite well.
On teleportation mechanic and room-scale VR
I can't wait to see how other developers approach this topic. I think full 360-degree hand tracking is going to be really important to making fully immersive games. It's tough to ask a player to always remember which way they're facing when the rest of the experience is so engaging!
How teleportation works in Arizona Sunshine
Before the player can move to a next location, he has to be eligible to do so. The eligibility check is varying for each location, but mostly comes down to: "am I safe to move." If met, we display a shootable button near the next location. Once shot, the screen fades to black rapidly, the player is teleported to the next location and the screen fades in again.
Prototyping and iteration
Initially we didn't consider teleportation as the way to move in Arizona. We have been playing with ideas ranging from free movement as in classic FPS' to being on the back of a pickup truck which drives through the game world. Free movement was quickly discarded as the nausea rate was high. We later moved away from the mobile design as well because rapid moving detailed environments also induced nausea.
Why the final design
Teleportation does not induce nausea in comparison to the other options. Also, we can design a player space around the room scale and keep non-interactable uninteresting stuff outside of the reachable area of the player. This way we can make the world feel vast and interesting when in reality only a small portion of the world is playable.
On teleportation mechanic and room-scale VR
There are two distinct ways of handling teleportation in VR being used right now. Our method is to enforce the offset position from the center of the player's room when moving to another location. The locations are positioned on the center of the player's room setup. This way, if a player is on the edge of his room, he will be on the edge of his location.
Another way is to not enforce this offset, but to always center the player on the location he is teleporting to. This means the player will have varying degrees of freedom for movement depending on where he was standing in his room before the move. This can be a good alternative for faster-paced teleportation where precision is key, but would not be ideal for Arizona.
How teleportation works in Defense Grid 2 VR
To teleport from "God View" to "Tower View" in Defense Grid 2 VR Enhanced Edition, the player looks at a location on the map and presses a button to teleport there. To keep the player comfortable, we always do a quick fade to black before moving the player to a new location or changing their scale. In our game, we also avoid rotating the player during teleportation to prevent them from losing their frame of reference. - Mike Smith, programmer
God View
Prototyping and iteration
We did most of our work on making it comfortable. We tried certain fades—fades to white, fades to blacks, certain speeds of fades, and it’s amazing how things can go from annoying to comfortable, just with small tweaks. We ended up tweaking the way we fade to black, and the way we fade back in so that it seems natural and doesn’t take too long, but doesn’t go so fast that it’s jarring. There’s a lot of iteration in that…The speed and time with which you fade down, the scale [of the area around you after you teleport], all make a difference.
The tower view came from a programmer who said, "I think I can do that," and he just put it in thinking everyone was going to hate this, but we all saw it and thought it was really cool. Then we wanted to figure out how to play the game from this view, and that’s where a lot of the work ended up being. - Jeff Pobst, CEO
Tower View
Why the final design
We really wanted to stick to the fact that you don’t get sick in our game. Who wants to buy an entertainment experience that has a percent of a chance of making you ill? I don’t think many people. We wanted to be that really solid entertainment experience that’s fun, great tower defense, strategy, puzzle, and it won’t make you sick. We’ve really held onto that…This game will not make you sick! - Jeff Pobst, CEO
How locomotion works in Land’s End
In Land's End you move around the world at walking pace, in a straight line between pre-defined points. Land's End is controlled entirely with head direction so you select where to move just by looking at a marker. We never actually teleport the player because we found it disrupts your sense of direction and immersion.
Prototyping and iteration
Land's End is a game about exploration and sense of place so finding a comfortable, immersive motion mechanic was the first thing we did. It took months of iteration and user-testing to get there, and the mechanic changed a lot over that time. Critically, we learned that the movement mechanic was intrinsically linked with the game design -- they both had to evolve in balance with each other. This seems to be a standard thing in VR -- you can't force the player experience to fit your design, you have to alter your design to fit what works well for the player.
Why the final design
Our priority was always to find a way of moving around that was comfortable and immersive so we quickly discarded teleportation (too disruptive) and traditional first-person gamepad control (too nauseating and required blindfold controller skillz). That left us with continuous straight-line movement and the challenge of how to make it feel natural. It took a long time to get it right but I think it was worth it. We've ended up with a mechanic that not only is really comfortable, even for the most sensitive players, but also feels incredibly natural so that players use it almost subconsciously. I think that's the sign of great design -- that users don't even notice it.
On locomotion mechanics and room-scale VR
We know that fast unpredictable movement will make the majority of VR users feel sick, so we need to come up with new ways to move players around in VR. For me, exploring new worlds is the most exciting part of VR and so it's incredibly important that we get it right. Land's End gets away with continuous movement because the whole game is designed around a relatively slow pace of play, but for larger environments or faster movement I don't see any alternative to using teleportation. Budget Cuts is the first implementation I've seen which could have a real chance of not only solving the problem but also opening up whole new avenues we've never thought of before. This is why VR is so exciting!
How teleportation works in The Gallery
The Gallery uses a system we call "Blink," that allows you to travel to wherever you’re looking, within a maximum distance. It also allows you to rotate your play volume, which can be useful when trying to fit multiple interactions into your room.
Prototyping and iteration
Previously we used regular analog stick movement, but when Valve showed us the Vive it became clear that traditional locomotion wasn’t the right way to go anymore. We spent about a week prototyping five different ideas to solve the problem, and teleportation was the clear winner. Valve had shown a similar system to us in the past, so we used those ideas in conjunction with our own to create a mechanic that worked well for The Gallery. The end result was something that allowed easy and comfortable traversal of the game world, without making you feel like a superhero.
Why the final design
The Gallery is a slow-paced exploration game, so the most important thing was that the locomotion was simple and transparent, and didn’t distract from the atmosphere of the game world. Interestingly, Myst used a similar mechanic to sidestep a different set of technical constraints way back in the early 90’s, and since that game was a huge inspiration for our project, teleportation ended up feeling very natural and even added to the nostalgia we were trying to evoke.
It was understood when playing Myst that you weren’t actually teleporting around the world. It was a sort of cinematic edit, rather than a superpower. Blink is designed to have that same feel, which is why we have footfall audio, and subtle timing differences depending on the distance you travel.
On teleportation mechanics and room-scale VR
I think we’re all just scratching the surface of what can be done here. The fact that there are already a number of good solutions less than a year after the Vive reveal is a very good sign. Room-scale VR games need to conform their design to these mechanics, however. Focusing on small scale detail rather than expansive open worlds seems to be a good starting point.
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