The 35s is a small game that I built from the ground up around one of my favorite locomotion styles in VR to date, jog-in-place. And what better way to stress test a locomotion system than to be chased by an ever growing mass of… creepy doll monsters? That’s the basic premise of The 35s.
Locomotion is one of the most fascinating problems VR faces today. Over the course of the last 5 years or so we’ve seen two major camps form in the locomotion interface landscape, teleportation and smooth locomotion. Each have their own set of trade-offs and each have an equally vocal base of advocates more than happy to explain why they find it the most suitable option.
Teleport tends to be the most comfortable option, it also can encourage players to physically engage with their playspace as more finite movement tends to be a little easier and takes a little less time. But it’s also a very unnatural locomotion style that isn’t cohesive with the way humans move through a space.
Smooth locomotion works like most traditional first person games; push the analog stick and your character will start gliding around the world. This movement style tends to feel more immersive as we can explore an environment in a much more natural way. It has a major trade-off though in that it can cause a lot of user discomfort in the form of motion sickness. There are tricks developers have found to mitigate this effect, like occluding the user’s peripheral vision during movement (what I use in the 35s). Also games like Echo VR have found a 1:1 motion with your arm and flinging yourself around a zero G environment can be surprisingly comfortable. The other and I think more concerning issue with smooth locomotion is that it tends to discourage user’s from physically engaging with their playspace. Our instincts drive us to solutions that require the least amount of energy to achieve a certain goal and in the case of movement, it’s a lot easier to stand still and glide your way closer to something, than it is to take a physical step forward even if that step forward would be more immersive or satisfying, like for instance stepping out from around a corner to take a shot in Rec Room paintball.
Jog-in-place is a method of locomotion designed to bridge that gap. The core concept is to listen to the headset’s positional movement in the Y direction (up and down) to derive when the user is jogging and how fast they are jogging and slide the character in tandem with that. The effect can be surprisingly convincing and it has a couple of advantages over the main two methods. We’re tying motion to a physical action which can feel more comfortable and the jostling of the inner ear helps mitigate motion sickness slightly. We also can now explore an environment in a more natural way while still engaging with our playspace physically.
Jog-in-place isn’t without it’s own tradeoffs though, namely, we are assuming when the headset is moving that the user must be jogging when they could be enacting a myriad of different actions. This means we have to filter out unwanted headset motion noise, and this isn’t an exact science, there are certain motions that are hard to distinguish between jogging and something else. Luckily there’s a lot we can do to mitigate this issue. There is another issue with jog-in-place which is that it is not compatible with disabled people, or people who simply prefer to play VR sitting down. There are work-arounds for this using a technique called arm-swinger which can be used as a fall-back system and further still you could fall back to a slowly ramped smooth locomotion (similar to Mirror’s Edge).
I hope that this, admittedly derpy attempt at a game might inspire other developers to consider adding jog-in-place or other similar more physically based locomotion methods to their VR experiences because I think it can add a lot of value for players who appreciate the physical aspect VR provides as a medium.
Thanks for reading and stay safe out there travelers!