This was the second PC game I ever played, I think, and I still play it occasionally. Even the keyboard controls have held up, or at least my fingers still remember it. iD may have sunk a bit these days, but they're still one of the almighty developers in my eyes.
Doom was the first video game deathmatch experience I had over a modem. Before that all I played was BBS door games like LORD and Tradewars. The first match didn't last too long as someone called and kicked me off but it was fun for the few minutes it lasted.
If memory serves he destroyed me.
I didn't get into deathmatch until Quake 2. I could still play Quake 2 deathmatch for hours right now and be perfectly happy.
Awesome.
The first shooter deathmatch I was heavy into was Quake. I got my first hub and we played that game at Starcraft/Quake LAN parties.
Starcraft is about 50% of college for me. That's what I remember most.
That and Final Fantasy VII