Guns? Check. Zombies? Of course. Pickups, level progression, scores, six-player co-op? All accounted for. Zero Latency ticks all the boxes, but this VR game goes far beyond anything you've ever tried: when one of my teammates comes face-to-face with the undead, he freaks out and leaps backwards – straight into me. I physically feel the force of the collision and stumble, slightly stunned, forgetting that there was an actual human behind that virtual character, in a way I've never experienced before.

With the virtual reality scene exploding all around us, I've excitedly dived into hands-on sessions with all the main headsets, and had a blast across the board. Even so, Zero Latency stands out as the most engrossing, transcendent, disorienting-but-in-a-good-way VR experience I've ever had. That's thanks to the concept of "free-roam virtual reality," which takes the HTC Vive's characteristic room-scale VR and cranks it up to fill a warehouse.

"Virtual reality is such a new medium and is very immersive in its own right," Zero Latency's CEO, Tim Ruse, tells Gizmag. "But when you start playing with an Oculus (Rift) and you can't move at all, or you start playing with a Vive and you can take two steps in any direction before you run out of tracking, you rapidly realize that VR has more to offer than just sitting in a chair watching pornography or playing a space shooter."

The goal of Zero Latency, he explains, was to explore that potential. After running a successful crowdfunding campaign, the game officially opened in August last year in a warehouse in the northern suburbs of Melbourne, Australia. The reaction has been overwhelmingly positive, culminating in the announcement earlier this month of a partnership with Sega to bring free-roam VR to Joypolis, the video game giant's indoor amusement park/arcade in Tokyo.

Using an inventive mix of consumer and custom tech, the game tracks up to six players within a 375 sq m (4,036 sq ft) space. "It's one of the biggest motion capture volumes on the planet," Ruse boasts. "James Cameron did it bigger with Avatar, but that's a high bar." A virtual world is mapped over it, which you move through using the most intuitive of control methods: your own two legs.

"Something quite magical happens when you take people's eyes and ears, and completely envelop them in that sensory experience," Ruse continues. "The walking somehow maps what they're feeling, what they're seeing, much stronger than if you're just sitting in a chair with a headset on and a controller."

After about an hour of hands-on time, we couldn't agree more.

The Zero Latency experience begins before you even enter the matrix. With all the equipment, the act of kitting up adds to the feeling that your squad is about to jump out of a plane into a warzone. First you slip on the custom-designed backpack, containing the PC that powers the whole experience.

"Wires suck, it's that simple," says Ruse. "And having cables attached to your head, to your PC, when you're trying to play, is not only uncomfortable, it's also dangerous in a living room setting."

Free-roam VR doesn't cut the cords that tether your at-home set to a computer or console, it just stashes them out of sight and out of tripping range. And it's effective: the pack felt like part of the costume, and within minutes I'd completely forgotten I was even wearing it.

Next is the headset, an Oculus Rift DK2 customized with a headband that holds a pair of glowing orbs straight off a Playstation Move wand. These are what allow the system to track users on such a large scale. A pair of Razer Kraken 7.1 Chroma headphones cap off the headwear.

And then there's the gun, a solid 2.5-kg (5.5-lb) prop rifle that absolutely feels like the real thing. This model, which the team affectionately calls the Blackbird, is the third iteration of what is essentially the game's controller. Two more PS Move orbs along the barrel track its motions with surprising precision.

I actually felt a little nervous as I was handed my gun. Being an awkward, gangly kinda guy, I trust my hands around a controller far more than my two left feet, so removing my sight from the equation while strapping a thousand-odd dollars worth of equipment to my body seemed like a recipe for disaster. Not to mention that I was sure I'd look like a noob holding the gun.

Then it hit me: all my teammates already had their headsets on. They were no longer in the warehouse, they were in a futuristic, virtual shooting range, and the only "me" they could see was the gruff army guy with my name floating above his head. And I didn't need to feel self-conscious about how the real me was holding the gun: my avatar had somehow decided that embedding the rifle in his chest was the best way to hold it.

Glancing around, I wasn't the only one who looked like a Cronenburg horror: Nick's head was on backwards, and Scott had his arms wrapped around his neck like a scarf. These movie monsters were laughing at each other, a sound that echoed creepily from both inside and outside the headphones at the same time.

But once our equipment was all set up, the tracking seemed to catch up, and our avatars began to look like actual people. Our task was simple: pass through a series of checkpoints, slaughtering zombies by the thousands along the way. Each set of checkpoints would load a new section of the level, redressing the warehouse floor as we moved back and forth across it.

In hindsight, the game itself felt somewhat dated in terms of complexity and visuals, an average-at-best zombie shooter if played on any other platform. But it works perfectly as a vehicle for the free-roam VR concept, keeping the core gameplay simple to allow the technology to really shine and ensure that gamers and non-gamers alike can pick it up with ease.

"You put someone who's, say, a decision-maker in their 60s, in the game, and they get comfortable very quickly, which is a great testament to how natural that feeling is," says Ruse. "They walk around a bit, and we've got a few tricks on how we integrate and ramp up the game intensity so they get comfortable before anything gnarly happens. It's very interesting to put people in it, and see people who are not gamers, not technology-focused, and within one or two minutes, they're walking around like soldiers."

It's not hard to see why. Like any VR experience, the first few minutes were spent gawping in awe at the environment around us, with the added excitement of being able to stroll around the room. It's hard to emphasize just how immersive that ability is. Treadmills like the Virtuix Omni try to capture that motion, but it just never quite feels natural.

In the beginning, my brain understood that I was blind to the environment my physical body was moving around in, and it was telling me to be super careful when I moved. But soon, I learnt to trust the design of the game and the space in the warehouse: obviously there's nothing on the floor, and the smooth concrete surface is perfectly even.

As your sense of presence in the real world fades, you'll find yourself walking around virtual walls and desks like they were really there, because as far as your instincts are concerned, they are. Technically, there's nothing stopping you walking through those obstacles, but your brain won't like it, and doing so kinda kills the immersion.

And besides, there's a chance that the in-game wall is mapped to a physical wall, and trying to phase through it will lead to your inclusion in a viral VR fail video. But it's not hard to avoid that fate, since the boundaries of the game space are clearly flagged in the form of red flashing barriers that pop up long before you give spectators a laugh. These warnings do break the immersion slightly, but it's a necessary safety feature.

A couple of minor niggles pulled us out of the experience. On occasion, when loading into a new section the guns would calibrate at the wrong angle, so your virtual rifle would point about 45 degrees to either side of where you aimed the physical one. Other tracking issues raised their heads too, and the game suffered the odd moment of repetition, but none of that really detracted from the experience.

No, what I'll remember is the genuine thrill of being forced to cross a thin makeshift bridge between two buildings, single file. I'll remember looking down at the ground, far below me, feeling the wind on my face as the team turned on actual fans in the far-off world of the warehouse. I wanted to walk over that edge, just to see what happened – would my character float or fall? – but I literally chickened out. That's a huge compliment to the reality of the technology.

And with the blank slate of the warehouse, the game itself can be swapped out and updated regularly. The game we played has been running since August, give or take a few patches, but Ruse says the goal is to eventually offer several different games a year, and develop the technology as a platform for third-party content.

"We have an SDK that we use internally, so we're looking at opening that up soon to start bringing other people in," he explains. "We're actively looking for partners that can help us to develop content, with a view to be like an app store where they can put their content, and if someone chooses to play it, then they get a piece of the action. It can be games, it could be educational, it's only really limited by your imagination."

To that end, the company recently announced plans to move to OSVR, a more open-source VR platform than, as Ruse describes it, the walled garden that Oculus has become.

Already, the system is being used to build virtual open houses for real estate, and training simulations for the army and firefighters. But it's the idea of playing a team deathmatch shooter, or a Portal-esque puzzler, or a survival horror game in free-roam VR, that makes me a little giddy.

The experience soon to be available in Sega's Tokyo amusement park shares a lot of DNA with the Melbourne game, but will be tweaked to suit local tastes. The early version we played felt much more arcadey, complete with points popping up over every hit and kill, and the ability to check your score by glancing down at your feet. Instead of progressing through linear levels, the scenario plants you in one location and tasks you with defending it from an encroaching zombie horde, using elevators, catwalks, exploding barrels and a barricade-repairing gun.

The deal with Sega is just the beginning for Zero Latency, with the company going all in on the idea that free-roam VR is a modern take on the arcade, a "destination experience," filling a social need that regular VR can't provide.

"Much like the birth of cinema, you can't get it at home," Ruse says. "People come and have this amazing, quite intimate experience with their friends, in this multimillion-dollar technology-laden warehouse."

Ruse was a bit coy about the company's plans after the expansion to Japan, but don't expect that to be the end of it.

"We've got a fantastic product and it's a world leader, it's ready to roll out," Ruse says. "So the next step is to put flagship sites in different markets around the world, focusing heavily on Europe and North America. And obviously Japan, Southeast Asia, and China, your major markets. And then from there, it's really global domination," he laughs.

With our mission a success, the five of us remove our headsets and return to the real world. As we hand back our gear, I have a weird urge to touch the table, just to check that it's really there.

Zero Latency is currently running sessions Wednesday to Sunday, for AU$88 (US$65) a head.

You can check out a preview of the experience headed to Japan in the video below.

Product Page: Zero Latency

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