Mario Kart and Mortal Kombat are great, but Wolfenstein 3D was really something special. I vote for Wolfenstein 3D.

Wolfenstein 3D was great. It kinda invented the modern shooter and although the levels were kinda repetitive, it was a lot of fun. On top of that, you were badass here in germany for playing the game as it was basically banned. =P

Desert Strike. I couldn't stop playing it. It was an unexpected masterpiece.

Also I want to mention
Gobliins 2
Dune 2
Bucky O'Hare
Mitsume ga Tooru
Darkwing Duck

I voted for Sonic 2. Imo, it's the best non-RPG of the generation. Top to bottom quality and fun. Sonic 2 is a Sonic game which really understands how to design levels which allow you to build up speed and use your momentum to discover secrets and perform cool tricks while still providing a good level of challenge. Masterpiece.

Anyway, I have to say that the Nintendo bias is getting crazy now. If Wolfenstein 3D can get a run-off and win, I would accept Sonic 2's loss, but Mario Kart? Really?? It's not even a good game. The later Mario Karts are great fun (still not GotY material), but the original on SNES is not at the same level. It really does feel like too many people will just vote for whatever Nintendo game came out that year like some kind of hive mind.

This one is really tough.

Between Ultima Underworld, whose influence is to be found in plethora of genres, Ultima VII, which is even today superior in many aspects to modern RPGs, Wolfenstein 3D that was the first FPS as we know them today, Alone in the Dark which was template for later survival horrors like RE and SH, and Dune II, which set template for RTS games.

Then there's pure fun games like Mario Kart, Mortal Kombat, Virtua Racing, Lost Vikings and Comanche: Maximum Overkill (I knew people who were buying PC for that due to its, for the time, mind blowing gfx).

Ultimately (pun intended), I have to go with Ultima (either one)...and since Underworld is in the poll, that will be my vote.

Honorable mention to Indiana Jones and the Fate of Atlantis, to this day one of the best point&click adventure games and Darklands, very ambitious open world RPG set in medieval Europe which is considered granddaddy of real time with pause combat in later Bioware's RPGs, as well as being one of the influences on Elder Scrolls (along Ultima... of course).

It's a bit of the same thing with Sonic as it is with Mario Kart. Most of the later Mario Karts are better than Super Mario Kart, but it was maybe The best racing game we had available back then, just like people remember the early Sonic games so fondly because they filled the void of platformers from Nintendo between Super Mario World and Donkey Kong Country. It's not like there weren't better platformers than what Sonics were, it's just that nobody was publishing them at the time. 

1992 was a great year for PC, so many new amazing games.

Dune and Dune 2 both came out in 1992, unheard of nowadays. Dune's intro alone was already mesmerizing.

The start menu screen was also great as a screen saver lol. The game was a pretty good adaptation of the book and dabbled into RTS in one of its later sections. At the end of the year Dune 2 came out, a spin off made around the RTS part, basically inventing the RTS genre.

Dune 2 was so good, from the voice samples to the diverse campaigns. You could complete the game as Artreides, Harkonnon or House Ordos, introduced for the game (not in the books). All 3 houses were distinct with their own 'cut scenes', units and special abilities. We played it a lot together in all kinds of different ways. We completed the campaign many times, used 'trainers' to shake things up where basically one of us played as game director adjusting things on the fly to keep the game edge of your seat.

Dune 2 also prompted me to learn how to make a mouse based GUI. The level data was all stored in text files (or xml) and I wrote a program to parse those and show it as a map on screen which you could modify with the mouse. That way we could quickly create new levels and skirmish maps, save and play them. From the wickedly evil, Harkonnen opponent starting out with lots of palaces for frequent aerial bombardments, to accelerated levels with abundant Spice starting with lots of harvesters and units from the start.
Dune 2 was truly ahead of its time.

1992 also saw Alone in the Dark which got me into the horror genre. Such a spooky atmospheric game

A precursor to Resident Evil, and I still like Alone in the Dark more than I ever did the Resident Evil games.

Links 386 Pro was mesmerizing with it's amazing visuals for the time

It was not real time rendered yet it rendered the location accurately from ever play your ball landed. Kinda like How Elite Dangerous now generates a new sky map every time you jump to a new solar system. The golf simulation was pretty good as well, addictive game.

Then there was Comanche Maximum Overkill wich blew my mind with its voxel based engine

It was incredible to fly over the terrain in a helicopter, this game felt so far ahead of its time. We played it in LAN configuration at work, hunting each other down in helicopters. The campaign was pretty good as well. Aces of the Pacific and Harrier Jump Jet also came out in 1992 yet Comanche stole the show with its voxel based engine, night vision flying and picture in picture views.

But in the end I have to give the year to Wolfenstein 3D, the game that started the modern FPS genre. The levels were full of secrets just like Mario. Always press on every wall cause you might find something. Some had to be opened in the right sequence, some hid power ups, some had level warps.
I played Wolfenstein 3D a lot while playing Trance music on the CD-Rom drive mixed in with the game SFX. Now those tracks on that CD are forever link with "Achtung" "Mein Leben" all the sound effects and vice versa. Wolfenstein 3D had iconic sound effects that are still instantly recognizable today.

It didn't take long until we had downloaded a texture editor for Wolf3D. Since we were 18 at the time it didn't take long to replace all the wall texture with porn we had downloaded from BBS. Wolf3D home made tits and ass edition. I also created a psychedelic edition and tricks to make levels seem bigger or smaller.
I've returned to Wolfenstein 3D with different remakes. The version on PS3 was the best, so fluent and fast with analog aiming, that sped up the game immensely and still as fun as it was in 1992. The later Wolfenstein games also added the original as easter egg.

Sonic 2 was great, but I have to give it to Mario Kart. To this day I don’t even bother with any other racing game.

Although it included some groundbreaking games, it honestly cannot be said that 1992 was a year in gaming I've ever felt all that strongly about. My favorite game from that year is definitely Alone in the Dark. Just a very ambient experience. Visually and musically impressive by the standards of its time too, and the writing and voice acting is solid and mood-setting!

In terms of console gaming, obviously Super Mario Kart has had the longest-term impact on this medium, not only in franchise sales terms or when it comes to getting other companies to try their hands (and generally fail) at replicating its success, but also in the sense that it inspired the big N to bring their trademark goofiness to other genres as well. Super Smash Bros. for fighting games and Splatoon for shooting games, for example, can be considered offshoots of the same principle that Super Mario Kart represented and probably wouldn't exist without it. It's cute and fun. It works.

Sonic 2 was of I think greater cultural impact contemporaneously though and is also frankly the more enjoyable game, IMO. Sonic 2 was the game that brought the blue blur into his own, more finely distinguishing the franchise from what Mario brought to the 2D platforming genre. Built to be a fast-paced experience, zones were shortened to two acts with fewer optional routes and made more numerous and varied in exchange and there were long stretches of relatively or completely danger-free turf where you could really ramp up Sonic's speed without adverse consequence. The game was built to provide the player a sense of momentum, and it works! Back in the day, I enjoyed nothing more than getting Sonic moving faster than the screen could. Also lots of the other trademarks of the Sonic franchise were introduced in this game, including Tails and the accompanying two-player options (including, notably, cooperative two-player, although it could be unwieldy and impractical outside of boss fights and special stages typically; something Mario did not offer as yet), 3D special stages, Super Sonic, Robo Sonic, and the Death Egg. And the Sky Chase Zone, which doesn't hold up tremendously well, but was a fan favorite at the time.

That said, if I had to name a personal second-favorite of mine from this year after Alone in the Dark, it would probably be Streets of Rage 2; the best entry in the franchise, nay genre, for decades to come in my view. The original Mortal Kombat was also a blast at the arcade and came with a bonus of enraging my parents with its use of blood, forcing me to sneak plays. The ninja aesthetic of it was also something distinct from what Street Fighter II offered, although it must be said that, as a play experience, it really didn't top Street Fighter II in my mind.

(Super Mario Land 2 is probably worth a cursory mention here as one of the best Game Boy games ever made. Although really Game Boy games don't generally hold up that well today, IMO.)

Totally agree, the Nintendo bias here is really through the roof. The original Mario Kart is incredibly clunky. Not even the best kart racer on the market at the time. Sonic the Hedgehog 2 was the best 2D platformer of the 4th generation and Streets of Rage 2 was the best brawler, those are imo the best games of 1992. Wolfenstein 3D is also a good choice, though it is harder for me to pick, as I feel ID software exceeded it in every possible way, already the next year.
Contra 3 also deserves consideration.