"Next, I'm going to take you deep underwater," a voice says quietly out of the tranquil darkness we're standing in. Our ears tell us we're underwater a fraction before the scene appears around us. "You're standing on the deck of a sunken wreck."
We look tentatively around the wreck's foredeck. The waters are crystal clear and far above us we can see the sun's broken rays refracting through the waters. There's a blissful tranquility, a sense of calm, as we gaze through scene surrounding us. The wonderfully enveloping soundscape matches the visual depths.
There's a rail at the edge of the deck and we take a few steps towards it. Small clusters of fish scatter as we move. We reach out to grab some, but they dart away, the light glistening off their scales as they slip through the water.
As we look over the railing, we're hit with a real sense of vertigo. With a sharp intake of breath, we look into the inky blackness of the depths beneath us, quickly stepping back from the edge.
Brave new virtual world
This is the moment that HTC Vive's virtual world becomes real. There is no ship, no railing. The vastness of the whale that glides up isn't real, but neither are there words to describe its scale as we turn around to look behind us.
But the vertigo is real. The emerging sense of wonder is real. The total immersion we're fooled into believing is real. The feeling that the Blu:Encounter from WEVR is giving us a VR experience like nothing we've ever seen before is very real indeed.
We're standing in a trade show meeting room at Mobile World Congress. It's the typical style, a temporary fabrication of lightweight walls topped with a cloth roof. It's ordinary in every sense imaginable, the very definition of bland.
There are two exceptions to the otherwise miserable formality of the room: the two laser units mounted on adjacent walls, and the HTC Vive demo unit we're wearing.
HTC Vive has been born out of HTC's partnership with Valve. Announced at Mobile World Congress, HTC Vive and Steam VR is taking virtual reality from a static seated or standing experience where you wiggle your head, to one that plays out like Star Trek's Holodeck, or virtual worlds imagined in The Matrix or Tron.
The lasers mounted on the walls transect the whole space. The Vive headset and controllers are covered with detection points, so they know exactly where they are within that space. That sort of 3D motion mapping isn't a new technology - it's similar to how Hollywood captures movement that then underpins CGI models in blockbuster movies.
But here it's used to let you roam in Vive's Full Room Scale virtual reality, meaning you have more freedoms than before. You can sit, stand, kneel, walk, jump, duck, dive, bob, weave, punch, skip, spin and probably stand on your head, and Vive knows what you're doing and where you're doing it.
We want to test the boundaries of this virtual world, so we start we're walking across a futuristic polygonal landscape stretching off over the horizon. There are some buildings a long way off and the shape of the ground keeps shifting around us. It briefly reminds us of an Inception dreamscape, before a blue grid softly appears in front of us.
That's Vive telling us where the wall is, like we've hit the edge of an arena in The Hunger Games. This is where the matrix ends. If we keep walking, we're going to hit the wall, and Valve's demo guy isn't going to be happy. This intro has been created by HTC Creative Labs to get you used to some of the control basics of Vive.
A square frame pops up around us, and the previous world bleaches grey. We're transitioning from one stage of the demo to the next.
The HTC Vive Controller has the same motion tracking that the headset does, meaning you always know where your hands are - you can see them, if they are hands. Unfortunately we don't have any images of them and in demo form they aren't the final thing either, so that probably doesn't matter.
The controllers have a trigger that's operated with a squeeze of your hands, and a touch sensitive pad on the top that you can use your thumbs to control. It feels natural and it's versatile, as our next demo will show.
It's a painting demo called TiltBrush, which has been seen before in VR on Oculus and Cardboard but now appears here in a new format. It gives us the chance to really put our hand controls to the test. Using the top pad of the right controller we can change the thickness of the painting tool we're using.
A squeeze of the trigger and there's a green light line painted as we scribble around. The left hand is much more exciting, however. A touch of the top pad and we're looking at our tool palette, But it's a carousel that rotates around our hand, letting us pick colours and tools. It's ultra futuristic, like a holographic wrist tool.
It's a special day when you get to paint your own rainbow across the sky. That compounds another eureka moment. We walk under our own rainbow and look at it from the other side. It's painted in a 3D world, the boundaries of two dimensions don't apply. We're giggling as we fill the room with colour, and walk around to inspect our handiwork from all sides. It's not art, but it is fun and it gets us thinking creatively.
One of the things we've noticed is how smooth the experience is. Graphically there's no sign of lag, no delay as you move your head, hands or body around. The display runs at 90fps, which should keep it all clear visually. There's no flicker and the headset is pretty comfortable too, with the soundtrack being completely enveloping.
To be fair, we've almost forgotten that we're wearing the demo rig - that's how immersive the experience is. But this is very much a developer demonstration. The thing we haven't said is that we're surrounded by wires.
The controllers are wired, although they will be wireless by the time they get into the hands of customers. The headset too is wired and occasionally we're stepping over the trunk of cabling in the room. It's strapped to our hip to take the weight and help everything move together, but we're subconsciously aware of it.
These are things that HTC and Valve will need to address as Vive evolves from demo unit, to final Developer Edition, and finally coming into the people's homes by the end of 2015.
We're plugged into a desktop PC with a monitoring station, where our Valve demo handler is running the show. But we've no idea what the real requirements will be for the hardware, or the specifications of the Vive headset itself. We can see there's an HDMI input and two USB inputs on the headset, but beyond that, we just don't know.
It's all about content
Our final demo is called Aperture and we get the feeling that Valve wants to have a little fun. We're in a workshop, being given instructions. They are pretty fast and we're wondering if something is going wrong. We open the door and Atlas, the robot from Portal 2, staggers in. It's time to run some repairs.
With a swipe of the hand, Atlas expands into an exploded component view across the room in front of you. It's incredibly detailed as you try to figure out how to repair the damaged robot. The instructions keep coming so fast that you have no idea what's been said. It's exhilarating, it's confusing, we're lost in Valve's world, puppets on a virtual string.
It's this use of existing and familiar characters that has us excited, especially when you're pairing the IP that Valve has, with a system that's so capable and dynamic.
But it's also obvious that the HTC Vive currently has some real challenges before it will work in a typical home environment. Content is going to be everything and content is where VR currently struggles. We've seen demos or showpieces from Cardboard to Gear VR, through to bigger systems like Oculus Rift, and this needs to be more than being able to look around the inside of a car, or falling out of a plane.
Yes, we have played Elite: Dangerous and Alien: Isolation on an Oculus headset in the past, but even they felt like test demos at the time (mainly because they were).
The real key is finding ways to make VR work in new ways. How do we use Vive's freedom of movement and what sort of play space will you need? Is this going to lead to people converting their garages into VR playrooms? Can we build a Holodeck in the garden?
But on the creative side, it's not going to be about isolated demos. Virtual reality will need worlds that can use the movement. Many VR experiences are confined to a seat, so how do you make movement work in games? Head movements make perfect sense, but what about running and sidestepping? How does this become a first person shooter experience for the mass market?
We've been wowed by HTC Vive, that much is obvious. The demo is really exciting, well beyond experiences of VR we've had in the past. That serves as a great showcase for what can be done, but to make this into the home there needs to be a rich variety of engaging content. It's going to be creative genius that makes a convincing argument for virtual reality at home, rather than the hardware itself.
We can expect to hear a lot more on Steam VR and from developers, as well as from Valve and HTC themselves. It's easy to cry out for a VR Half-Life or Portal experience, but to invest in HTC Vive, you going to need lots to do and lots of play with.
The Developer Edition is launching in "spring", with the aim of bringing the consumer edition out before Christmas 2015. There's been no mention of price, specs or anything else at this time.
We'll be watching eagerly, as we have high hopes for this next step into a brave new virtual world.