My first experience with Doom was shortly after it released; A friend from school invited me over to his house so I could copy the floppy diskettes of Doom shareware. I installed it on our family's Gateway 486DX. I could never figure out how to get the mouse working in DOS, and someone messed up our sound card trying 'fix' something else, so I enjoyed Doom with PC-speaker SFX for years.
My best-friend and I, being mall rats, were at the mall one Friday night. We stopped in Electronics Botique and I spied the Doom shareware on CD for $7. My funds being only $5, I decided to take the easy way out and steal it.
I eventually convinced mom to buy me Ultimate Doom on CD, and Doom II. Later I would use my allowance money to buy Master Levels and some huge book called "Tricks of the Doom Programming Gurus", though I never delved into level editing. A couple years later, our PC bit the dust.
My main gaming system became the SNES, which I bought Doom for when that released. I would go on to play that over the XBAND modem; there was one guy in my city who played Doom, so I wouldn't have to pay long-distance charges. Or, my mother wouldn't ;).
My next Doom game was for the PlayStation. I remember convincing my brother to get the same game as me as a gift so we could play coop. We had him drag the living room TV into my room so we could play LAN games. It was amazing. I was blown away by the PlayStation version's sound effects, and to this day often use psxsounds.wad when playing Doom on PC.
I rented Doom64 at one point, and was shocked at how different it was. But I loved it.
I was 18 and would start thinking about moving out soon, but not before we got another family computer. It was an 800mhz Compaq Presario. I discovered Doom95, and fell in love with the vanilla game all over again. I would soon learn how to download custom wads and haven't stopped since. After building my own PC a year later, I taught myself how to use a level editor at a basic level. I completed one map a couple years later (see attachment). I hope to do another someday. I also have a half-complete layout for a DM level that I'd like to get back to.