The criteria of "influential" is a good one, which sets some different constraints from the more common and more amorphous "best" list. I tackled this many years ago, but enough time has passed that I thought it would be good to take a fresh crack at it. Gaider's original criteria is:
As someone working in the industry, and an avid gamer, what would you say are the games that influence the way you think about games today? The ones that have stuck with you, and which you hold up as the bar—either for their story, their gameplay, or their sheer fun factor—by which you measure other games you play?Now, I don't work in the industry, and while I've fiddled around with making games (from QBASIC up through Shadowrun Returns campaigns), my output isn't nearly broad enough to be able to point to a wide array of influences. That said, I think a ton about games, and definitely have a measuring bar by which I judge new games. (Along the same lines, this list definitely skews more towards the genres I enjoy.)
Gaider's list includes only pre-2000 games; my own spills slightly past that, but due to how the question is framed, it still skews slightly older. Ranking these was hard and should be taken with a massive grain of salt.
With no further ado, here we go!
- Ultima VI. The first Ultima I played, it remains a highlight of open-ended storytelling. The game's total freedom was absolutely astonishing: you could instantly pop over to the other side of the world, slay the "bad guys", and lose the game; or you could wander in the wilderness, stumbling across hidden secrets and useful nicknacks; spend the day manually harvesting cotton from the fields, then spinning it into thread, weaving it into cloth, and cutting it into trousers; flirt with gypsies and rob peoples' houses. At the same time, you traveled with a tightly-knit party of old friends and new, who bantered with one another and played their own roles (Iolo strumming his lute as you lay by the campfire, eating your meal before turning in for the night). We have some wonderful games today, but I don't think any modern game has managed to recapture Britannia's breadth and depth along with the storytelling power of that game. (Not to mention it being one of the first games to actually do something interesting with the concept of racism in a fantasy setting.)
- Civilization. As with David Gaider, I'd hold up the fourth entry (along with Fall from Heaven 2) as the best, although 1 and 2 were probably more personally formative as they were my main introduction to turn-based strategy games. Furthermore, they were the first commercial games I ever modded, and I gained a deep appreciation for the wonderful new life that could be injected into good games when developers made core files available in easily-edited and easily-extended formats like plain text, XML and unencrypted image files.
- Baldur's Gate 2. While it traded away the open world freedom of the Ultima series and the exploration element of its own predecessor, it more than made up for it with the astonishing depth of its characters and plotlines. The Viconia romance still haunts me, and the Aerie romance still cheers me; those were the first times I'd encountered this sort of player-directed romance in a game, and I have yet to find anything as compelling in a non-BioWare game. And, of course, the core systems are just fantastic, rewarding careful planning and execution of combat while also allowing for a tremendous variety in the ways you build your character and party.
- Planescape: Torment. Man, this game is so good on so many levels. It's probably the most literate game I've ever played, combining both an incredibly deep story and an astonishingly broad range of ways to roleplay your character. What I love most about it, though, is the way it upended my assumptions about how these sorts of games "should" work, utterly destroying fantasy RPG tropes and inverting the way I typically played these games. After being trained to always protect my PC and sacrifice my NPCs in Baldur's Gate, Planescape got me to do the opposite. I also continue to be impressed at how relentlessly dark this game allowed itself to be, without even the patina of gallows humor that I would have expected.
- Hero's Quest. This was the first truly graphical game I played, and probably the one that made me first fall in love with gaming. It also introduced me to the adventure game genre and the RPG genre. Much of the referential humor went over my head at the time, but I still found plenty to chuckle at, along with some surprisingly dark sections. This game brought together exploration, combat, classes, skill advancement, economy, and many other elements that I take for granted today. The later Quest for Glory games were good as well, but also grew more linear. I used to dream about how wonderful it would be to just live in Spielberg, enjoying the beauty of Erana's Peace and the waterfalls and dryad forest and all the colorful townsfolk.
- System Shock 2. In my opinion, this game has the most effective sound design and the scariest villain ever created in a video game, even fifteen years later. The BioShock games crib heavily from the playbook they perfected here, but for my money, this remains the definitive reference for how to terrify players by manipulating sound and integrating it into the environment. Plus it had a cool story, impressive plot twists, and a really excellent RPG progression system that the later BioShock games largely ditched.
- Grand Theft Auto 3. As you can probably tell, I love open-world games, and GTA3 was a revelation to me: I finally realized that it was possible to have an open world in a game that wasn't an RPG and not set in a fantasy world. As in games like Ultima VI, I loved the unstructured fun of just wandering around, poking my head into random places, gradually building up my mental map of where things lived. To me, GTA: San Andreas is the pinnacle of the franchise, but GTA3 was the one that shocked me out of some long-held ideas about video game genres.
- Maniac Mansion. It's really hard to pick a single LucasArts adventure game, but this was my first exposure and the one that's stuck most firmly in my head. They had wonderful humor, baffling-yet-logical puzzles, and a deep commitment to whatever strange world they had created. I was excited to discover that the game included multiple endings, some of which I didn't find out about until years later. I also remain impressed by what they were able to do with a multiple-character "party" in an adventure game, as well as the really-well developed Ed/Meteor family.
- ICO. One of a handful of precious games that I value for their ability to instill a feeling of empathy in me. The game managed to do it with virtually no dialogue, but a really novel use of several other tools at its disposal (most memorably the vibrating controller, which did a surprisingly good job at simulating the pulse of a young girl you were leading by the hand). The core gameplay was solid, and the visual design breathtaking, but I'll most strongly remember the profound sense of responsibility I felt towards protecting Yorda.
- Shadowrun, specifically the SNES game. I had a mind-blowing epiphany moment when I was able to acquire a ticket to enter The Cage, sidled past the troll bouncer, then advanced to a soundstage, the music growing louder, as lights and pyrotechnics flashed around me, watching couples grooving on the dance floor, while Maria Mercurial stood triumphant at the front of the stage, belting out her song. It broke down the division I'd unconsciously been maintaining between the real world and the game world: games didn't have to portray fantastic otherworldly spaces and actions, they could also include aspects from our actual lives and experiences. Shadowrun was also my first-ever exposure to the cyberpunk genre; it would be many years before I continued my exploration of ICE and chrome, but it remains my baseline for grim techno-futurism.