Virtual Reality.
If you're reading this and you haven't tried VR yet - I can't recommend it highly enough. Particularly a higher end experience connected to a PC with tracking (HTC Vive, Oculus Rift, or Valve Index). The lower end ones like a gear VR are fun and novel but it just isn't the same experience.
I have introduced dozens of people to VR for the first and you just can't explain it to people. Videos are no help. Trying to describe is better than nothing I guess but it just doesn't get you there. If you take anything away from this comment it would be to just try to find somewhere that you can try VR yourself and you'll understand what I'm about to say better than I could ever explain it.
The equipment available to consumers today is pretty low end compared to what is possible with prototypes / commercial systems when it comes to resolution, framerate, and other factors. There are also quality of life features that work but haven't been brought to market yet for consumers. Things like wireless for the headsets. But even with this early days tech - when you put the headset on you feel like you are being transported to a different place.
If you've tried VR you probably know what I'm talking about. There is this distinct feeling of being present in the virtual world. Remembering places in VR feels more like remembering a physical location you've been to rather than something you saw in a computer game. And VR is going to be so much more than games.
Because of this feeling of presence - going places in VR actually feels like going to a different place. Likewise, when you meet someone in VR it feels different than meeting someone in a fourm like this or even in a voice chat in a video game. It feels closer to actually being in a room with them. I think a lot of this is related to being able to see some of their body language.
Everything in VR feels like a hacked together prototype and works like one too. I like to show VR to people but I can't really recommend it to most people because it just doesn't work well enough for them to be able to fix it when various things break or settings need to be changed. Some options that I offer to them are things like PSVR or I've heard the new Oculus Quest is pretty good as a casual experience but I haven't tried it yet. But both of those route you to walled gardens that are missing a lot of the really cool stuff.
If you know the right nooks and crannies to look there are some amazing things to see and do. I'll list a couple of my favorites but the best ones all have something in common. They are a platform that allow people to make their own content. In some cases they are made that way on purpose, others it feels more like an accident of design.
Remember when the internet was a little younger and you'd find a cool or bizarre website in an irc channel or something and think "who even made this?" Well that time is back except you can't view it through a screen anymore. You have to put on an HMD and venture directly into the internet. When you take a walk through the internet what do you find? Mostly weird stuff and brief glimpses of the future - both are worthwhile.
VRChat is probably the best example of the above. Like everything in VR the interfaces are terrible and everything half works. But even through that fog you start to get an idea of how deep this rabbit hole goes. In VRChat you choose an Avatar and then go to virtual worlds and meet people other people. They have default Avatars and Worlds to choose from but the best content is what people make themselves. It's a unity game and there is a shocking degree of freedom in what people can upload (content made with apps like blender or unity itself).
Copyright may as well not exist yet in VR because it's too new for anyone to know to look. So people decide to be various superheros or characters from all kinds of fiction. I once visited a world where you could choose from hundreds of Marvel and DC characters. It's not that in VRChat you can be Spiderman. It's that you can choose from dozens of spidermen from various comics and movies (the real spiderverse perhaps).
As you might expect there is a lot of anime. There are also a lot of unconventional avatars. Sometimes People choose to be a car. Or a firetruck. Or a toaster. Or an ATM Machine. Sometimes people choose to be something incredibly large like a robot towering hundreds of feet in the air. Sometimes people choose to be a tiny avatar like a mouse or an RC car.
The strange thing is that there is a sense of scale in VR. So if you are a giant robot, everyone looks small and you really do feel like you are that large. Likewise if you pick a tiny avatar everything in the world looks giant. This feeling of presence remains. A very present toaster.
For many users of VRChat the Avatars are the most compelling parts. Don't get me wrong, they are really cool. It's amazing to see some of the things that people come up with. Especially the avatars that have some sort of animation without it being obnoxious / trolling (hey I did say we were walking into the internet here). People spend hours creating these versions of their virtual selves and build in abilities to do things in game. Most of these things just boil down to character animations or sounds. Any animation or sound you want leaves a lot of room for creativity (with few limits on size, or unfortunately volume).
But to me this isn't the real draw of VRChat. The worlds are. You can look at the most popular worlds in the game in menu but I prefer the search bar (searching is one of the things that half works.) Being able to be some character from fiction or someones imagination is one thing - but being able to travel somewhere is another thing all together.
So you may find yourself in a VR bar or arcade having a conversation when someone drops a portal to another world. Some of my favorites I've been to include a recreation of the secret base containing the Stargate from the show by the same name. Once you're there you can dial the gate and walk through to find yourself walking out of a pyramid on a desert planet called Abydos. Or you may find yourself climbing into a helicopter with friends in a world of abstract and surrealist art created to go along with an album somebody made. A sort of VR music video that you can fly through to a soundtrack. Or if a helicopter doesn't suit you how about another world where you can put on a jetpack and fly through what feels like various settings on an old media player visualizer (avoid this one if you get motion sickness!). Or how about one of those rides from a theme park where they put you in a hydraulic car that doesn't move and project a "ride" onto the screen in front of you? Because yes, somehow people have put a couple of these in VR too (I like the Back To The Future one).
There are literally thousands of these worlds you can visit. It really reminds me of the old internet where you would find these amazing little things tucked away and hidden.
The community is probably closer to today's internet as far as signal to noise ratio goes. But if you're willing to look there are definitely kind and interesting people to meet as well.
VRChat is fun and interesting but it's actually not where I spend most of my time in VR.
In VR there are maybe a dozen first person shooter games to choose from. In VR shooter games kind of feel like a mix between a game and paintball or something like that. My favorite is called Pavlov VR. It is a shameless knock off of counter-strike (I mean shameless. Down to the same exact same guns, mechanics, and win conditions.) But thats ok! Because it means you can play counter-strike in VR. Which is incredibly fun. There are also Call of Duty clones, Battlefield clones, and Battle Royale games. But what makes pavlov so special is that you can upload maps, similar to VRChat. Just like VRChat it's boundless creativity.
So in addition to having all the same mechanics as counter-strike it also has all the same maps. I've been playing Dust II for years (not as long as some, never did play 1.6). But now I get to actually run around there. Same goes for maps from a lot of other games I used to play. In addition to people uploading maps they also turn them into these custom game modes that you can instantly play just by joining or starting a server. Because of this, Pavlov winds up feeling like lots of different games. There are the classic default modes but there are also lots of other game modes to try (zombies, duel servers, conversions for weapons). Some of the coop modes are fun because they are a more social experience like VRChat but there is more to do. VRChat can wind up a little boring just standing around sometimes.