Yeah, he was the first "serious" fantasy author I started reading after Dragonlance - Midkemia is the world the created and used for their TTRPG campaign in college. He's still writing books today, but he's getting old. "Magician" is still among my favorite books of all time, it had a huge impact on the entire genre. I reread it last year, one of the few times I'm not disappointed when reading something from my youth. 

The "Betrayal at Krondor" book is terrific as well, and the sequels are also good. I'm still pissed off at how he handled Locklear in a stand-alone novel later on though. Due to the games, and the books by Feist, Jimmy the Hand is my all-time favorite book character, I think he features, or is at least mentioned, in something like 14-15 books in total (and his ending is epic). 

Has to be original Zelda and metroid. Open world, especially given the release date, and metroid had connected levels which are still a huge thing today.

The Getaway - Mapped out a nearly 1 to 1 section of London that it was set in, no hud or map, cover based shooting, recovering health (you knew how injured you were by the PC limping, you recovered by resting), it was being a "cinematic" game long before the idea even came about.

This kind of makes me want to play the game. Somewhat surprisingly I don't own it yet though (but it doesn't seem too expensive!), and I have too much to do at the moment anyway, so this'll have to wait. Still, sounds like an interesting game.

It got a sequel that had nothing to do with the Midkemia setting, it was a decent enough game but all the hype disappeared when they lost the license. 

BaK is a classic gem, but a tough sell for younger, modern gamers, its looks are dated, and the mechanics are a bit clunky by modern standards. It's an amazing game though, it has a really good story and some amazing characters, the music is also awesome. A friend of mine sometimes plays "This Kingdom Mine" on guitar, it always sends me right back to my childhood when I watched my foster-brother play the game. I could sit for hours while he explored Midkemia and killed goblins, dark-elves, pirates, wyverns and all manner of creatures and enemies. 

BaK is considered to be one of the most influential RPGs of all time, along with the likes of Ultima Underworld, Final Fantasy, and Baldur's Gate. But, due to the license being lost and no other studio showing interest in the IP after "Return to Krondor" got a lukewarm reception, the entire IP disappeared from the gaming space and is mostly known among 40+ gamers who happened to own a PC in the early 90s and the nascent PC gaming scene at the start of the Golden Age. 

The game that inspired this thread was I bought the Nightdive remaster of Turok: Dinosaur Hunter, which I never got to play as a kid as games with realistic violence weren't allowed in our household, and I was shocked at how despite being an early N64 game from 1997, it felt more like a Gamecube/Xbox era game in its movement and character/camera animation which made it feel so much more fluid and grounded than other shooters of its era.

There's probably other and maybe better examples of destruction than Red Faction Guerilla.

But I played Red Faction Guerilla recently and the destruction is just so damn good. That games 16 years old now, where the hell did all the physics based destruction mechanics in games go?

Unreal came out just before Half-Life and was similarly a shooter with more story in it than the ordinary mid-90's FPS.

Populous was something that didn't exist back then and is sadly rare still today.

And Ultima Underworld, open world 3D action-RPG with various factions to ally yourself with etc.
I was particularly impressed with how many ways there were to open doors: find a key, pick the lock, use magic to open door or you can just smash the door open by hitting it with your weapon (potentially damaging or breaking the weapon).

Donkey Kong Country imo, at the time people were blown away by those visuals in the SNES.

Crysis, from a technical POV.

Chrono Trigger from a "RPGs peaked with this game" POV.

Here are some that come to mind in roughly chronological order:

Adventure - This action/adventure game was popular on the Atari 2600 during an era where people mostly bought the system for console ports.  So many design basics in both action/adventure and action/rpg games can be traced back to Adventure.
Tempest - An intense 3D action game from the year 1981...way ahead of it's time.

Ultima 3 - Not the best in the Ultima series, and yet most JRPG's can trace their game mechanics back to this.
Ultima 4 - Arguably is the best in the Ultima series and is so ahead of it's time that no one has tried to copy or improve on it since.  

The Legend of Zelda (NES) - The #1 reason the arcades died.  This type of game would neither work in arcades nor on the computers of the time.  You had to get a console to get this kind of experience.
Metroid - A platformer that scrolls both vertically and horizontally.  Also another game that where you needed a console to get this kind of experience.
Mike Tyson's Punch Out!! - Dark Souls combat is highly inspired by this game.  It was also probably the best looking game on the NES.

Super Mario Bros 3 - I italicized this, because this is probably the most impressive game on this list.  Keep in mind that the killer app that launched the Famicom was Donkey Kong (arcade port).  Super Mario Bros 1 became the NES's top killer app, because it was leaps and bounds ahead of Donkey Kong.  It introduced side scrolling, music and a lot of other staples in gaming that many other NES games copied.  And yet Super Mario Bros 3 is just so far beyond Super Mario Bros 1.  All of this gaming evolution happened on the same console.  It's just so amazing to see gaming progress from Donkey Kong to SMB 3 and yet both were killer apps on the same console.

Civilization - It invented 4X games and really popularized strategy games in general.  I still meet young people today that love playing Civilization and yet the current games are just elaborations on the same basic formula.  The best part of this game is still some similar experience to where you develop tanks and then roll over some other civilization with warriors or a phalanx.  A timeless, classic design.

The Secret of Monkey Island - The character design and world building is still better than most modern games.

Final Fantasy 4 - This is the first video game I played where I actually cared about the story.  It was done so well, that the story is still more engaging than 99% of other video games.
Shining Force - Every good tactical game that has followed owes a lot to Shining Force.

Dungeon Keeper (1 & 2) - These games basically invented the Tower Defense genre many years before anyone knew this genre existed.
Ultima Online - Made MMO's a thing before anyone thought this type of game had a market.

Grand Theft Auto 3 - I've never actually played this game, but I've played a lot of 3D open world action games that would never exist if it hadn't been for GTA3.
World of Warcraft - There are two types of MMO's.  Those made before WoW and those made after.  The two types are very noticeably different.

Wii Sports - Motion Controls are a permanent part of gaming and it started here.
Minecraft - This game now fulfills the role that Legos used to play in the lives of young children.