Doom always reminds me of my first first person shooter multiplayer experience.
My friend got his first 1x CDROM/Soundcard package for his 486 SX 25, and it came with a bunch of free games. We haggled and traded these crappy games at our local computer shop for a Null Model Cable, after discovering the Intersrv.exe and Interlnk.exe files and reading the help
After enormous amounts of trial and error, tweaking config.sys and auto exec.bat, we were able to copy the doom.exe using a null model transfer to another computer, and have player vs player games. We had a lot of fun and felt like this was the cutting edge of gaming, or at least in our world.
Doom for me is the foundation of all modern multiplayer games, regardless of it was the first - i still have fond memories of where it all started for me. It's mind blowing to think about the games industry these days and how it's evolved.
We didn't have search engines or ways to connect with other people of similar minds to solve the problems that we encounter. From these early gaming experiences I learnt enough about DOS and the PC to make it my hobby and later my career.
I owe Doom more than just many hours of entertainment, in a round-about way.