Quake, doom, heritic
The one i played and invested most was UT2004 and Tribes 1 and 2… I loved Tribes skiing mechanics
Counter Strike 1.6. LAN party at school computer lab with the boys.
Unreal tournament. I was very young but my dad would let me play it on his computer when I went to visit him at his house.
Think I was about 5 when I first played. Obviously was terrible lol
Half-Life Counter-Strike. I played a lot of wc3/hero modded counter strike. So even before TF I was playing hero based shooters lol. Also a lot of scoutzknivez.
First one I ever played was Duke Numem 3D….but I just wasn’t into pc gaming at the time…I was around for wolfenstein and doom and such
CS 1.6 then Source, Then Halo A lot of Halo
Halo Custom Edition because I was a poor rat kid.
First FPS was pixelated original Doom.
Online, I think quake arena. But I played that on my roommate’s PC in college.
First online shooter for my own system that I could afford, either Battlefield 2 or Quake. Just can’t remember which one cause that PC fried out ages ago.
Those were fun days because half the floor on my dorm were competing and a friend of us on the opposite side of the building got the entire dorm on a server once our campus installed high speed in all the dorms.
Madden, Quake, Tekken Tag and Soul Caliber 1-2 was all we were playing back then. Oh and offline Mario Kart, Smash, and Golden Eye 64
Wolfenstein 3D for Windows 3.1.
But my first multiplayer game was Tribes 1.
Here’s a server modification I worked on for Tribes 1. With about 40 servers running it, 2 years of tournament play, across about 20 teams.
It had 10 character Classes, with different loadouts and abilities.
Spy, Scout, Alien, Juggernaught, Mercenary, Engineer, etc
Along with about 40 different types of deployables. And I write a rapid deploy script called greydrop to spam those, which became part of the meta.
Overwatch, lol
like ever-ever: i played rainbow 6 rogue spear when i was like 9 or 10
but i barely played it and eventually settled on playing mmos and single player games for years.
The first counter strike even before v1.6 i think.
wow you guys make me feel so young i was born that year 
Metroid prime hunters.
Mine was overwatch! It was like my gateway into some other fps games - I had never played anything like this before. I was more of a minecraft and stardew valley gamer but since overwatch I tried fortnite, valorant and apex legends. I didn’t like any of them as much as overwatch though.
I mean you are welcome!
Just you wait when someone makes a topic 12 years from now on, when overwatch 9 or reforged (or classic ololol) will be the actual version, and someone creates similar topic asking everyone their first mp game, and you gonna say ‘‘it was overwatch 2’’ and someone will say: ‘‘Wow you make me feel so young…’’
You immediately gonna feel as old and bad, as i feel right now reading your message…
ExpelMarkmywordsliarmus! swish and flicks at shoegazer
Call of Duty Black Ops. I remember that was when the transition happened. I used to be FGC and I got online set up specifically for Mortal Kombat 9; however, I decided to also give Black Ops a try because my cousin said it was really good and you could level up guns and customize your class. I thought it was more of an RPG type thing. 
Anyways, I started having a lot more fun shooting people than beating them up. The netcode was awful in MK9 (and I was on Wi-Fi). I couldn’t believe how drewful it felt because I was used to playing on LAN. That perhaps contributed to my strange shift from fighting games to shooters. Not that Black Ops was great, but I was such a scrub that I believed the people killing me before I could react was just because they were better. 
My first FPS, was…the first FPS (or well, one of the first): Wolfenstein, not the one released in the 20xx but the one that looked worse than Minecraft 
. Back then it was and looked really cool though, also sort of revolutionary for its time. Wasn’t online though.
I’m already starting to feel it but not to that extent yet. Saw my 7 year old cousin, born after Overwatch was released (how) playing Fortnite and it blew my mind
Not an fps but my first shooter game was plants vs zombies gw2 which was where i met my freind which showed me overwatch