"What? Lol. It's not anything like a holodeck. You can only walk about six feet! You can't feel objects, there's no wind, there's no smells, you've got a damn great cable attached to your head, and the other characters are just computer game NPCs!"

But there are still plenty of limitations to it, and you may well be listing them in your head as you read this.

The new wave of VR is a huge step in that direction. By "The New Wave" here I mean the Vive, the Oculus Rift, and - if reports are to be believed - Microsoft's Mixed Reality. Phone VR with no positional tracking or motion-tracked controllers is not the same thing at all , and should really not be taken as a representation of current VR. If the VR system doesn't allow you to get up (using your IRL body, not a controller), walk around a bit, and pick things up with your hands (mediated by controllers like Oculus Touch or the Vive wand) I would argue it's not "real" VR, and it's certainly not what I'm talking about here.

Ever since its introduction, a lot of people have regarded the Holodeck as the ultimate goal of games or virtual reality. A tool that can create a completely convincing world in which you can be anything you want to be.

(Also, for storytelling reasons, it bugged out more often than Internet Explorer 6. I'm pleased to say current VR tech, including Left-Hand Path, doesn't have quite that problem.)

If you don't know - the "holodeck" was the invention of Star Trek: The Next Generation. Ostensibly a recreational tool, it could conjure in perfect detail any environment its user could dream of. For plot reasons, the utility's obvious - as Wikipedia says,

And if I was speaking to someone whom I suspected might have watched Star Trek - you know, about 80% of the population - I might follow that up with "basically, I have a holodeck".

(My creative approach - latest output of which is the VR horror/rpg Left-Hand Path - definitely tends in a certain direction, and that direction is deep, complex magic systems and disturbing consequences therof. Plus I was really inspired by Dark Souls this time around.)

That's... quite the sales pitch. And I don't mean "making worlds" as a novelist or even a filmmaker (my former career) does it. I mean creating worlds you can walk into, explore, interact with, and get murdered by hideous creatures brought back to life by the blasphemous rules of the magical place you now inhabit.

People sometimes ask me why I'm so keen on VR - keen enough to drop a 20-year career to move into it - and I always give the same response.

Losing The Wire

Wireless VR is pretty much a solved problem at this point.

The Vive has the TPCast wireless module, which gets some rather mixed reviews from users, but does work. More wireless solutions are on their way - notably one from Intel.

Meanwhile, Oculus have announced a completely untethered wireless headset and controller - the Oculus Go. It doesn't even need a computer - everything's contained in the headset. It's coming next year, and would be my current pick for the thing most likely to spark the next wave of VR adoption.

Walkin' On (Virtual) Sunshine

Locomotion. It's the bête noir of VR developers right now.

Put simply: most people don't have an infinite plane in their apartments. Even people living in Texas.

So if you jump into the endless vistas of Skyrim, say, or even the dank corridors of Nehemoth in Left-Hand Path, and you wander them freely, sooner or later you'll be interrupted by face meeting wall.

The default solutions to this problem at the moment are either an in-game "teleport" mechanic - which works well but breaks immersion for some people, and obviously isn't as good as walking - or a game-like "sliding" mechanic - which again, breaks immersion, and also causes some people to throw up.

In Left-Hand Path, you play a wizard, and so I wrote it into the background that one of the features of your powers was the ability to "blink" from place to place. (You can also use sliding locomotion, because wizards have feet too.) But that's a rather game-specific solution.

Some games and experiences have experimented with redirected walking or environmental redirection. Basically, you can fool the human brain into thinking that you're walking in a straight line or exploring a large environment, when you're really, really not. Notably, the VR game Unseen Diplomacy does this to great effect, fooling you into thinking you're in a much larger environment:

https://www.youtube.com/watch?v=KirQtdsG5yE

But this approach only works under some circumstances, and it requires you to have a rather large room.

You can enhance the effect with Galvanic Vestibular Stimulation, but then you're using magnets to alter your brain, with more or less unknown medical consequences. For some reason users seem not to go for that so much.

More promising approaches are mostly variants on the "treadmill" theme. The Virtuix Omni is the only one that's made it to market so far, and reviewers are not too enthusiastic:

Our best description of the experience is to imagine that you're moonwalking on the sides of a human-sized serving plate, while wearing slippery bowling shoes.

But people are continuing to develop new treadmills, and sooner or later they may hit on a winner. The Strider treadmill is getting better reviews, using a bunch of rotating balls underfoot. The KatVR is close to launch, and again, seems to be getting better reviews than the Omni. And there are literally dozens more - including some really ambitious stuff like the giant-robot-arm plan from AxonVR, of whom more below, and entire floors made of robot-controlled mini-treadmills.

And there are other approaches too - step-trackers, where you walk in place and the software detects your movements. "Arm-Swinger" locomotion, where swinging your arms as if you're walking translates into movement. "Grab And Pull" movement where you grab the air and pull to move forward.

With so much research and experimentation going on, and some of these approaches showing promise, I'm pretty sure we'll have an acceptable walking solution sooner or later.

Haptics

This one's a harder problem.

Basically, you can see things in VR, but you can't feel them. And of particular importance, they can't stop your movement or interfere with it.

Problem #1 for pretty much any VR game developer is "how do you stop the player sticking their head through a wall". That's a haptics issue. So is allowing monsters to parry a sword strike, or allowing players to feel the recoil of a gun, or any other physical sensation.

Most controllers have limited haptic feedback, like a games controller. They can vibrate more or less, and if that's used intelligently it can add a remarkable amount of depth. If you get the chance, play "Longbow" from Valve's VR showcase "The Lab" to get a feel of just how much you can do with a simple vibrating controller.

Haptics is a huge, huge field of research - there are at least two separate haptics conferences, and dozens if not hundreds of companies working in the space. And there are a number of approaches that are showing progress on at least some aspects.

For touch, there's an ultrasound-based approach which appears to work remarkably well. It only works for soft touches, and is more bringing the sensation of touch into the virtual world rather than putting any force there, but it's still a significant leap forward.

Likewise, Tactical Haptics has been working for years on controllers that will simulate limited inertia and force.

This is actually a huge deal - I've been working on swordplay in VR recently for my next project, and the fact that the swords are weightless is a real immersion-killer, and rather hard to solve. From what I've read in hands-on reports, the Tactical Haptics addons do quite a good job adding the sensation that you're holding a heavy, hard to move object, or getting force feedback as you use that object in VR.

One really neat haptics device sounds pretty strange initially - a VR fan. Yep, it's a fan hooked up to your computer that simulates airflow whilst you're in VR. Weird, but users report it's a surprisingly significant addition to immersion in racing games or similar experiences.

In terms of actual "hard" feedback - a swing of a sword being parried or a wall blocking your progress - the only active project I'm aware of is the somewhat terrifying HaptX exoskeleton. This uses - or will eventually use - a giant robot arm and attached exoskeleton to provide a two-in-one solution to walking (you walk, your feet move, the robot compensates) and haptic feedback up to and including movement-stopping feedback. However, I can't find any videos of a working suit yet so this one's definitely some distance off.

Smell

You might assume that smell in VR is definitely in the "yeah, no progress" category. You'd be wrong.

8k VR headset Pimax has promised a "scent module" as an optional addon to their headset. No real news on how it'll work, but they say that it's coming.

Meanwhile, in New York there's a company dedicated to nothing but making VR smell real.

And there are more. There's a porn company also working on a scent module. Multiple other startups. Here's a roundup of the state of the fart - erm, I mean, art.

I look forward to testing the "scorched flesh", "squamous, dripping slime", "magically-opened demonic rift" and "rotting corpse that should have died ages since" smells for the upcoming Left-Hand Path smell-o-vision edition.

And Beyond!

There are more problems left to solve, of course.

We've still got to figure out how to create convincing human NPCs for VR - although there's plenty of movement on all fronts there, from programatically-created movement (either using reinforcement learning or clever algorithms) to natural language. Or we could just hire actors.

We've got to increase the visual fidelity of the environments - but that's going rather well at the moment. On the hardware front, the first 8k headset was recently Kickstarted, and whilst Oculus have said in the past we'll need to go past 8k for really realistic displays, we're clearly heading in the right direction.

There are plenty of problems that you might not even think of standing between reality and the Holodeck too. For example, equiloproprioception is surprisingly important in Actual Reality, and aside from the aforementioned magnets-affecting-your-brain tech, we're still in the very early stages of figuring out how to mess with that. How will we simulate humidity? What about air pressure? And so on. But there are smart people working on virtually (no pun intended) all of these.

And of course we've still got to invent the revolutionary technology which lets the entire thing malfunction and dump you in a real Western where you have to become an outlaw to survive, and bullets can really kill.

But I'm OK with waiting for that one.