Street Fighter 2 definitely. Pretty much created the genre we know today.

Zelda is my pick, but what a year. Almost any other year and Street Fighter 2, Final Fantasy IV, Metroid 2, and Sonic could have won easily.

I'm tempted to go with Wing Commander 2 or Monkey Island 2, big personal favorites.
Lemmings is certainly notable and it's hard to ignore Sonic.
Scorched Earth needs to be mentioned as something I still play now and then.
Space Quest IV is one of very best Sierra adventures.

But have to give it to Civilization, for its part in both general and personal gaming history.

As much as I like Super Castelvania IV (sic), ALttP is still the the favourite.

A Link to the Past for sure. Even if I prefer the 3D games, LttP was the beginning of greatness for the series and honestly a big step up from anything that came before it in my eyes.

Didn't like FF4 and I've never gotten that far in Sonic.

Many many good ones.
I picked FF4 because I still think this one is far and beyond the best FF game of the original 5, and I still play it every few years to this day. It’s also to this day the most expensive game I ever owned because #1 I’d been reading about this game in magazines and had to have it, #2 this was one of the first import games for SNES. I don’t recall the exact price, but I remember it was about double the price of a usual game.

Sid Meier’s Civilization is one I feel is worth mentioning, and I played it a lot as a kid. But it was Civilization 2 that was most meaningful - Civ 2 was the game where I learned XML, pixel art, modding, and design - later on there would be a feature to add macros. Civ 2, IMO is what catapulted 4X into the forefront of strategy gaming and made Civ a household name and the holy grail of strategy games for years to come; but it all started with Civ 1.

Link to the Past - not much needs to be said, but this game for me was my favourite Zelda prior to Breath of the Wild, and aside from a period of time where I preferred Ocarina of Time, but soon after found myself coming back to LttP more frequently.

Metroid 2 was surprisingly good for a GB game, it had several upgrades over the first Metroid, and more complex villains, but was more a linear experience as you had to hunt down X-number of mutating metroids before continuing the game.

Streets of Rage is one of the best looking games of its time, despite not having the graphical fidelity of some of its contemporaries. Playing it on 3DS with the 3D parallax graphics is my favourite way to do this game.
Super Castlevania, Turtles 3, and Turtles in Time were other great side scrolling action games, both also worth playing today - even for non-fans of the franchise. Although, I preferred Dracula’s Curse because of the much wider array of features and freedom, Super Castlevania was definitely a better action game, and perhaps as good as the action ever got in Castlevania - as they toned it back in every later sequel I ever played. Turtles in Time was an arcade classic - Turtles 3 I didn’t play, although I was aware of its existence via magazines and chatter - I remember assuming Hyperstone Heist was the third game for the longest time.

Sonic the Hedgehog became my favourite platformer of the 16-bit era until Sonic 2. It’s on the easier side, and that’s probably its major downfall as Sonic 2 and 3, as well as other platformers were eventually going to beat it in terms of graphics and features. Sonic 2 is a significantly more challenging game, has more features (including tails co-op), greater graphical fidelity, and is about double the length; but this game has the honour of being the first of the franchise.

Street Fighter 2 was the first major fighting game, and also a significantly more popular fighter than any game that came since - there were multiple versions of Street Fighter 2, and it was (for years) the most popular game at the arcades - there were usually lineups and audiences.

Interesting to see how things are turning out so far. I knew Zelda would get a lot of votes, but I had no idea which other game(s) would get a significant number. I haven't played FF4 since 1991. It's probably a game I should revisit again.

Space Quest 4 was awesome. It came of 6 discs, which meant a lot of disc swapping while back tracking. It also too 30 to 45 seconds for each scene to load. The CD-rom version came out in 1992. We did have an early CD Rom drive where you had to put the CDs in a tray first before inserting.

Loading was pretty slow, taking 5 to 10 seconds to load a picture. Yet with a sound card you could already play your own music mixed with the game sfx while playing.

Space Quest 4 was worth the long loading screens, so much humor packed in one game. Tons of of fun. I should replay it some time, the vga version was quite pretty as well.

Now this is a serious year.

I think, when assessing what should be GotY we need to asses both the quality of the release istelf and the impact on the gaming industry as a whole. When using this method of analysis, I think there are 2 games which fulfil one criterion and there are 2 which fulfil both.

Sonic the Hedgehog was obviously a phenomenon and a cultural zeitgeist which launched Sega and the Mega Drive to not just compete with, but for a time, even overtake Nintendo. However, I feel that it is a game with inconsistent quality. Green Hill and Starlight are fantastic zones but conversely Marble and Labyrinth are abysmal and fail to understand that the ability to gain and enjoy speed through clever and skillful use of momentum are what makes Sonic so good. Therefore, I can't give Sonic 1 the nod for GotY, but if Sonic 2 can build on the good and eliminate the bad next year...

A Link to the Past meanwhile has the opposite problem. The quality is clearly there with this game and it's just as enjoyable today as it was 30 years ago so I see why it's leading the poll. However, the truth is that this game just didn't have that much influence on the industry. Sure there have been some ALttP clones over the years but it never changed gaming like say Ocarina did with the way we play 3D games (ie Z targeting and such). I do feel like there's merit to the argument that some Nintendo fans will come onto a poll like this, vote for Zelda (or Mario), and then move on without a second thought. Obviously, not everybody, but enough to make a difference.

Moving on to the 2 I think are worthy winners. Street Fighter II clearly had the quality and is also still fun to this day, but it also single-handedly popularised the fighting game genre. Fighting games are not my thing, so I won't personally be voting for it, but definitely deserves our recognition.

Finally, my vote will be going to Final Fantasy IV. This game was incrdibly influential in how it focused on storytelling and characterisation, which is somehting that not only RPGs but now many other games continue to do today. It proved that video games could be a serious medium for storytelling just like books or films. Furthermore, the game still holds up with the quality today. I do think FF would still hit even great from FFVI, but IV still stands proudly today as a classic RPG which can be enjoyed for both its story and ATB gameplay even over 30 years later.

For games on the list, A Link to the Past.

For games released in NA in 1991, Final Fantasy IV.