I have created and started documenting ideas for how this would work

How would what work?

Is it possible?

Is what possible? You don't make it clear at all what you're talking about. Presumably you're talking about creating some kind of game and presumably you have little or no experience.

All I can say is that to create most games takes years of slave-like work hours for potentially no reward..it's especially easy for an indie team to not be awarded at all for their work. To escape this trap you need to be very clever in game design and programming to figure out a game that maximizes the HowFunTheGameIs/AmountOfProgrammingRequired ratio. Using a game engine does NOT help in any significant way in maximizing this ratio.

Most people will tell you that you need to create many shitty games to be able to create a good game, this is not my opinion. Creating games takes a long time and creating a shitty game is a complete waste of time that only delays your ability to create a good game. What you need to do is if you're a programmer is to constantly seek out more info. Starting with how all the programming language features are implemented, to how compilers are created, how networking works, how operating systems work, how game engines work, how graphics APIs work, how the CPU works, how to make cache-friendly programs, how to write SIMD code, how engines implement lag-compensation, how TCP works, how UDP works, how does your engine abstract multiplayer state for example by treating data as events (sent once) and state (perhaps sent multiple times based on priority if UDP, once if TCP), how servers work, non-blocking vs blocking server implementation, Linux epoll vs select vs poll, why are garbage collectors a bad idea, how malloc is implemented, common Linux and Windows API functions and capabilities, how do engines implement multithreading (such as task-based dependency graphs providing task and data parallelism using worker threads eating from work queue), GPU lighting and compute shaders, BRDF lighting or 'traditional', precomputed GI?, forward or deferred rendering, gamma correctness, HDR lighting, DX11/OpenGL or DX12/Vulkan (would you gain from the newer APIs?), etc. This is especially true if you are working alone. If you have others working with you then you can specialize more in one or a few areas which I advice you to do. I will do that eventually myself.

Once you are done with this and have also had a few years of thinking about all the possible games you can create and all the details on how you would implement their features if the game is technically challenging (I iterate over the course of years how to implement game features for a very technically advanced/challenging game I'm creating that maximizes the ratio I talked about before), how your game would get noticed without a marketing budget, and such then you can create a prefect well-selling game on your first try (that's what I'm doing)!

The other option is to think you can create a game that'll let you be your own boss in two years using your current skills. Good luck with that, you'd have to be incredible at game design. Don't worry, this all only takes a few years which may seem like a long time but trust me, if you were to look back in a few years boy would you be glad if you did this instead of tried making a crappy game taking years of slave work that would end up giving you a total of 3 sales with little skill improvement to show for the work done.

I assume he's talking about this: http://swordartonline.wikia.com/wiki/NerveGear

Ahh you may be right. I just looked up Sword Art Online and saw that it is about being locked in a virtual MMORPG, and with his last topic being about creating an MMORPG I asummed the question was about creating an MMORPG instead of a question about the interface between brain senses and the game.

What I can say now Green Fox is the more of an expert you become in a field the better your ideas become in that field and also across fields, so keep learning.

Possible: Not now.

I believe this is actually being tested, but not in the recreative sense. Tuning into the nervous system has been attempted and, at least until the early 2000s, contraptions have been devised to receive and send directed energy inputs into both nervous and brain systems through such targeted systems.

The problem is signal encoding/decoding and understanding exactly what we're sending/receiving and how to insure it does what we intend for it to "do".

Unlike a computer which we've previously built, we know relatively very little about nerves (any decent Neurologist will humbly tell you that much) and brain in general and we're much more concerned with treating patients than creating forms of entertainments.

That being said, once sufficient medical breakthroughs have made these more common knowledge and that the technology is more commonplace, it will be imaginable to have this kind of hardware more readily available for developer use. Unlike AR tech which could not necessarily have medical use and does not compete with medical treatment capabilities, the cost of option here is dire.

Possible: Not now.

I believe this is actually being tested, but not in the recreative sense. Tuning into the nervous system has been attempted and, at least until the early 2000s, contraptions have been devised to receive and send directed energy inputs into both nervous and brain systems through such targeted systems.

The problem is signal encoding/decoding and understanding exactly what we're sending/receiving and how to insure it does what we intend for it to "do".

Unlike a computer which we've previously built, we know relatively very little about nerves (any decent Neurologist will humbly tell you that much) and brain in general and we're much more concerned with treating patients than creating forms of entertainments.

That being said, once sufficient medical breakthroughs have made these more common knowledge and that the technology is more commonplace, it will be imaginable to have this kind of hardware more readily available for developer use. Unlike AR tech which could not necessarily have medical use and does not compete with medical treatment capabilities, the cost of option here is dire.

Well, "this" certainly is not being tested. "Something" that is to the fictional NerveGear what the Stoneage Spear is to a railgun is certainly being tested now.

Does it ROUGHLY work the same way a future nervegear COULD work (in the sense "stimulates the brain with some kind of electrodes")? Yes. Does it allow you to live inside of a virtual reality with all your senses? No.

Green Fox, you are likely 20-30 years to early with that, and that is optimistic. In 10 years VR might have really taken off, maybe the brain is understood well enough by then to really start working on brain stimulation techniques that are precise enough to proejct images, sounds or smell/taste directly to the brain.

Give the thing at least another 10 years to be developed to a point where all 6 senses are stimulated with enough accuracy to not constantly break the immersion by lag and errors.

Then comes the time needed to make it safe to use...

On the last thing, also factor the time in such tech will need to actually pass government approval.

I am sure it will come one day. But there is a long and thorny road ahead, and as the anime/manga/books you are referencing is actually pointing out, there are many, many severe problems that will need to be addressed before releasing such a product. If an incident like the one in the first series would happen in the real world, IDK how long the technology would be quarantined... maybe it would be flat out banned in most countries.

Hacking your whole virtual life is bad enough... but when human lifes can be "hacked", most western government will not let people experiment for long.

Even if those hurdles are cleared, you will have created a device that with some minor tweaks and lots of experimentation can essentially control a person's brain. It's likely that creation of such devices will be banned as the potential for misuse is astoundingly high. It would allow someone to completely violate someone else's individuality at the most fundamental level.

The "Matrix" would be upon us... might just come at the same time our machine overlords finally decide to take over.

All hail the wachowski brothers, for they have gifted us with a glimpse of our future.