VR Gameplay Mechanics In 'Killing Floor: Incursion'

It may come as a surprise to you that it was a surprise to some of Oculus’ choice game developers when the company announced roomscale tracking for the Rift at last week’s Oculus Connect 3 (OC3) event.

In fact, the first thing I thought when the roomscale feature (not to mention the Guardian safety system) was announced from the OC3 stage was, "Uh oh, what's Tripwire going to do with Killing Floor: Incursion?"

The Problem Of VR Navigation

Navigating in a VR environment was one of the first problems game designers had to solve. Early on, between the camera motion- and low FPS-induced nausea as well as the lack of controllers and roomscale tracking, moving anywhere in VR was next to impossible.

Game devs had to get creative, and creative they were. They created teleportation systems, which can work whether you’re using a gamepad or Vive or Touch controllers. With the gamepad, you could look at a spot and press a button to instantly travel there. Now, you can aim a controller at a spot within the virtual world and click to move there.

There are a couple of other options, such as the touchpad motion that Onward’s developer chose to use, and a solution called Armswinger, in which you swing your arms back and forth beside you as if you were in a brisk walk. The touchpad motion is more comfortable than using a thumbstick on a gamepad because you still have your hands in the game, but it’s not a perfect solution. Armswinger wouldn’t work well in a shooter because your hands have to be down to your sides.

With roomscale VR, the problem is slightly compounded. Yes, you can walk a short distance, but you still have to teleport to cover long distances, and you need a safety system to keep you from bumping into or whacking physical objects. (Enter the HTC Vive’s chaperone system and Oculus’ new Guardian system.)

Solutions, Such As They Are

The day before the opening OC3 keynote, we had enjoyed demos of a number of VR titles. Immediately after I played Killing Floor: Incursion, I was making mental notes for the article I planned to write:

The game is fun and scary. Love the two-person partner system. Aiming at distances is hard. The knife-and-pistol loadout is my favorite. Navigation needs a lot of work.

In Killing Floor: Incursion, Tripwire had to solve all of the aforementioned navigation issues, and more. You have to move around in a large virtual space; in the demo, we stomped through a darkened wood before entering an abandoned house that promised to be full of horrors. Short of a VR treadmill, the only way to traverse those areas was with a point-and-move navigation system, which Tripwire employed.

The other major issue was that, unlike many VR games wherein the action is always coming at you from the front, Tripwire needed to figure out how to deal with your back. A key part of Killing Floor’s appeal is having to deal with zombies sneak-attacking you from behind. That seems to be a simple enough problem to solve--but only if you have roomscale tracking.

As I mentioned, the day before Oculus’ big roomscale announcement, not all the devs--including Tripwire--knew anything about it. “We learned about it the same time you did, at the keynote,” one developer told me.

So, short of a roomscale option, Tripwire’s workaround was a snap mechanic: You can move your head around, but to position your body to face a certain way, you have to snap the left joystick. That is, it’s not a gradual movement; each sharp jab of the joystick snaps you several degrees left or right. (I don’t recall how many “stops” were in a complete 360-degree circle, but it was at least four.)

The other major problem was that, because the game begs you to turn around all the time, your instinct is to physically turn instead of using the snap mechanic. If you turn your head, though, the Constellation cameras lose tracking. When that happened, I’d see TripWire’s “Guard Rail”--a simple, flat green-ish blue grid--pop up to tell me that I needed to turn my head back around.

This is, as you might guess, disorienting. Layer in a dark and purposely murky environment, and just getting around takes up quite a bit of mental energy. I kept losing my bearings.

This game needed roomscale tracking in a bad way. As is, the movement mechanics were kind of a mess.

No Half Measures

Ironically, what I initially saw as a half-measure--the wholly imperfect snap-to-turn mechanic--showed the Tripwire team’s forethought. They needed a placeholder mechanic until roomscale became available. They knew it was going to be just a matter of time until it arrived, but they needed to build navigation into the game in the meantime.

However, even as they built the snap mechanic (and Guard Rail) as a tweener solution, they were also already developing the game to take advantage of roomscale tracking. Thus, when I went back to the Killing Floor demo cubicle area after the keynote, I was expecting to see distress. Instead, I saw a knowing smile on the Tripwire rep’s face. They were ready.

Oculus’ roomscale solution is not complex. You just add a third Constellation camera behind you. Thus, it should be easy for developers to implement.

The TripWire guys made a bit of a gamble but, wisely, also had a backup plan. They wanted to build the game they wanted to build, and they stuck with that vision, knowing that Killing Floor: Incursion needed roomscale to really work, but not knowing when it was coming. In the meantime, they had a functional game ready to show.

Killing Floor: Incursion was a fun but flawed demo when we first played it, but the addition of roomscale tracking will eliminate almost all of the issues we found with it.

Now we just need a better way to traverse long distances. (Oh Virtuix Omni, you cannot arrive too soon.)

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