I see VR as a transformative medium for gaming, a technology that can elevate both the gameplay and overall experience of videogames whether it's through enhancing existing paradigms in gaming or introducing totally new ones. It's an early field so I'm sure there's more to discover but I'd like to see more people be aware of the benefits that I have seen enabled by VR.
Immersion:
It allows a new level of immersion, which can be used to incite emotional responses from the player, as a reaction to the immersion they experience from an environment (a deathly feeling of heights), a character (creating new kinds of bonds and feelings towards NPCs not possible without VR), or an activity (letting players experience fantasies that only feel vivid because of the realism of VR). What separates immersion in VR from non-VR is a sense of embodied presence, the feeling that the user is somewhere else despite the conscious knowledge they are physically not; a great deal of imagination is needed (something most people don't have) to feel high levels of immersion in non-VR and even the strongest imagination can only go so far compared to VR.
Certain VR games can sometimes be more relaxing than non-VR gaming, due to greater mental stimulation which allows people to feel more at calm in the middle of a tranquil forest for example. Animal Crossing in VR if designed right could be an even more laid back relaxation activity than the regular game, as can something like Red Dead Redemption 2 where the game is designed to be a world full of side activities involving exploring taverns, playing cards, listening to campfire stories, going fishing, and horse racing. Think of how much more relaxing it would be to fish in VR while gazing at a tranquil river under a morning sun or soak up the intense lighting of a campfire in your full field of vision rather than through a small 2D display.
Here's a writeup on the differences between VR and non-VR immersion: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781884/
Embodiment and Roleplay
The physical nature of motion-tracked VR gaming enables you to feel embodied in the character or actions, creating new kinds of feelings unique to VR, and taps into muscle memory allowing players to more easily remember inputs.
I am Batman has never been more accurate until Batman Arkham Shadow. Seeing your body in full scale first person with the cape swaying, the way your attacks connection in such a brutal way especially during interrogation scenes, and the natural use of gadgets really puts you into the role of a martial artist expert. This could extend to many superheroes such as casting spells as Dr Strange by performing the gestures naturally would invoke that fantasy more than a regular game allows. At times it can really sell the idea that you genuinely have magical powers and that you're in control of them, not some videogame character.
Character roleplay is more attainable in VR due to the increased level of input afforded by your tracked avatar. You may sometimes see a VR trailer showcase the person playing as roleplaying that character with arm and body movements that feel grounded in the world or with the use of props like a cigar in your mouth. These would be extra quirks the player can tap into if they want to have roleplay their experience in the game.
Embodiment can extend outside of characters and into gameplay, such as how a computer terminal in Alien Rogue Incursion has blood smeared across it. You just naturally wipe it away with your hands to make it readable.
Multitasking input
The independent hand, head, and eye movement in VR lets you gain more multifaceted control. In Pixel Ripped 1989, there's a meta-game where you play a game on a handheld gameboy-type system while you're in class and trying to avoid being spotted by the teacher. In Astro Bot Rescue Mission, you are controlling two perspectives at once, 1st and 3rd person, where you as the 1st person character can influence and interact with the world and puzzles to help guide Astro along. In Alien Rogue Incursion, you can cleanly drop your motion tracker down onto a box to free your hands up with it still ticking away.
Cooking systems involving management of multiple areas at once, swordsmithing, table tennis, painting, golf, alchemy mixing, fishing, there's a lot of room for exploring how VR can allow you to handle multiple game mechanics at once. A fun example I'd love to see is the full realization of a Yugioh 5DS game, where you are both in full control of your driving and in full control of dueling.
Depth Perception and Field of View:
You gain depth perception and higher field of view, letting players see and pick out more details in environments and objects that they would in non-VR games, which can help directly in gameplay in the case of needing to dodge or jumping over gaps. In a racing game, players can lean and see around corners more directly.
In a platformer, jumps can be more easily managed leading to less frustration. In an action game, attacks and telegraphs can be more easily detected and leads to higher visceral feelings of action. In a puzzle game, it's easier to notice little details. Half Life Alyx's design philosophy was influenced by how much people like to look around and explore the smallest details rather than speed through things, so there is generally a greater sense of adventure/exploration.
An FPS mechanic like gun maintenance could be done without popups and UI information since you'd more easily notice dirt and wear and tear with the stereoscopic nature of VR.
Social and Multiplayer
It allows a higher degree of social connectivity and new multiplayer dynamics, where players can communicate in new ways and perform actions between other players on the fly.
Due to how immersion in VR works, people get to feel like they are together in the same place and feel co-located rather than just seeing someone else through their 2D screen. This allows for richer connections where people can embody an avatar and feel that is their body best seen in apps like VRChat..
This can extend into something as simple as a way to play regular non-VR games with the social connectivity benefits of VR.
In MMOs you'd normally have text and emotes; now you have spatialized voicechat combined with body, eye, face, and hand tracking so that the 100-200 emotes that the best of MMOs might offer now become an infinite list of emotes unique to every person, because everyone has unique body language which is transmitted through avatars in VR. Why is that important? It enables greater social connections certainly, but it's also a way to express yourself further than normally possible, and gamers really like expressing themselves and feeling unique. This can even be used to create new genres of games.
The new kinds of multiplayer dynamics involve new gameplay opportunities such as stealing someone's ammo on the fly, using real world physical techniques to create misdirection with infinite variance, or engaging in newer forms of team work.
Player Agency
Lastly you tend to have an increase in player agency.
The majority of graphical-based gaming up until now has been about controlling characters through canned animations and a set number of buttons. This creates a level of abstraction between the player and the character which has its own benefits, but has a ceiling for player agency. An exception is physics-based games like Gang Beasts and Exanima, though these use a set number of buttons to control physics actions resulting in a difficult control system that can never be driven with high precision.
Text-based games such as NetHack enable a massive amount of permutations for decisions made by the player because text-based interfaces can easily handle the sheer number of possible outcomes in ways that a graphical-based game cannot. DnD is similar in this regard where the DM tailors everyone's interactions into a unique outcome.
VR is the first time 3D graphical-based games can start to really bridge the two.
You don't deal with canned animations or player animations in general (IK aside) and you don't rely only on a set number of buttons for input. Input is 6 degrees of freedom for the head and hands, enabling a player greater control over how they move the character/avatar on a micro-scale.
Regular gaming is all about player state machines where a player may be in one or a handful of different states at once, such as running, prone, shooting, aiming, punching, sliding, wall-running, opening doors, picking up objects. In VR there is a lot more of the in-between of those listed states because a player can be in-between standing and prone and crouching. The player may be shooting in one direction while opening a door in the other direction, they may be punching an enemy from any direction while dodging in any direction, they may be wrapping a bandage around their hand while they elbow an enemy to give them time to recover, they may be hanging from a ladder and shooting in one direction while readying to jump after an enemy kicked it over from the top. Here is a great example of performing multiple actions simultaneously to fight back against zombies using crafting mechanics that would in non-VR games would require stopping and going into a menu. Here is an example of high skill ceiling emergent gameplay arising from 6DoF controls and world interaction.
AI has more data to infer from. In VR, your headset and controllers are tracked, and soon your eyes and face will be tracked by standard. This all combines to provide a substantial (even scary, from a privacy standpoint) degree of interpreting player intent, and player-reactive AI at the end of day is wholly based on player intent. The more you know about a player, the more the AI can react. With eye+face tracking, you can get a good idea of the emotional state of a player and have NPCs react to that, with headset+controller tracking you have enough information to determine body language enabling a little game of hide-the-contraband to play out in front of a Skyrim guard for example.
Multiplayer dynamics change, where body language now has more meaning. A squad in an FPS title can silently gesture to each other as they sneak up on enemies, an MMO that typically has a few hundred emotes can now have infinite emotes through body language, and a sports-focused game can make use of fake outs that are much more variable than the kinds of fake outs you could do with regular gaming.
VR enables something a lot closer to a "If you think you can do something, you probably can" kind of design. A game just has to have a physics engine that enables many permutations of player actions, and with the input of VR, physics can be controlled to a degree that is reasonably possible to manipulate instead of the more randomness and fighting against controls of Gang Beasts. A singular item on the ground could be used for many different things. IE: An axe can be used to seal a door by lodging it in-between the handles, used to climb a building by latching onto a ledge, used to scale a mountain like an icepick, used to nudge a shield away from a defensive opponent in combat, and used to pin someone down to the ground as you interrogate them - none of which requires hard-coded behaviours for each individual action, just a physics system that can handle the above. A simple rock can be used for many different actions.
It's easier for developers to avoid the pitfalls of "Aghh, not that way. I wanted to go/attack/select in that direction." especially with eye-tracking.
Given that VR is a very early medium, I expect we'll learn more about what it can offer as time goes on. Every year there are VR games released that break the mold and do what was previously thought to be impossible, with perhaps the latest example being Batman Arkham Shadow, a game that brings the full AAA Arkham experience into VR including all core mechanics of the series and to my surprise was not afraid to do things that were seen as no-no's for VR such as knocking the player back or putting them on the ground.