I was there right at the start, when Wolfenstein 3D became the first proper FPS. I remember hearing rumblings of a new game that was coming out and then suddenly there was a shareware release on the fido net. I remember downloading it and being blown away by a completely different style of gaming.
I played the first Wolfenstein and Doom and Duke Nukem 3D over and over again. Only ever "completing" them once but there were so many MODS and WADS that you could keep playing without having to buy new games. They were incredibly replayable.
Wolfenstein 3D
Doom
Duke Nukem 3D
Star Wars Jedi Outcast
For years, FPS games were my most played games, not because I loved them so much but because there were just so many of them being made and, more importantly, they so often had cheat codes which would enable people to actually complete them.
There was a mid-period of FPS games, between the classics (1990s) and now (2020s), where there were a whole heap of great games that came out that had better graphics or interesting mechanics.
Unreal I and II
The monsters in this one would talk to each other and would run off to fetch their friends if you let them. Notable for the first "Smart AI" in a game.
Quake I and II
Moodier graphics than doom, though never quite matching the "hell" of the last levels of Doom 1, Quake was faster, gorier and darker.
Hexen 2
Following Hexen 1, and the two Heretic Games, Hexen 2 started to lean into adventure game and RPG territory. It was notable for being something different.
Rise of the Triad
Wolfenstein without the racial overtones but you knew what this one was. ROTT also had moving platforms, spike traps, monk puddings and magic mushrooms.
Doom 1 (and hundreds of other WADs)
Doom 2: Hell on Earth (and hundreds of other WADs)
Doom 3 and Resurrection of Evil
Half Life
Heretic 1 & 2
Hexen 1 & 2
Rise of the Triad
Duke Nukem 3D
Wolfenstein 3D
Return to Castle Wolfenstein
Quake 1 & 2
Star Wars Dark Forces (played the original, finished the 2020s remake).
Star Wars Dark Forces 2: Jedi Knight
Star Wars: Jedi Outcast
Unreal 1 and 2
Bioshock 1 and 2
Doom 3 R
Half Life 2
Halo
Star Wars Battlefront I and II (Classic and Remastered)
Star Wars Battlefront I New version (Also played Battlefront II New but didn't like it).
Modern FPS are an odd bunch. For a start, they're not all shooters, some don't even have guns. They're also not necessarily 100% "first person". Finally, they have better stories these days and feel like a blend of the old FPS and Adventure Games (and sometimes RPGs).
Darksiders
This was as close as I've ever come to feeling like I was playing God of War on a PC. Of course, it got too hard in the end.
Batman Arkham Asylum
A gritty and realistic Batman game. I loved the way they leaned into the detective side of his nature. I was enjoying it until I couldn't beat Bane.
Star Wars Battlefront
The 2015 version of Battlefront was quite good. It took me ten years to get around to playing it but by then it was fast on my PC and all bugs were fixed.
Injustice: Gods Among Us 1 and 2
What if Superman went bad? That's a pretty common Superman story and there's a few games like this now but these two were some of the best.