First time I saw Doom was at the exchange on base while I was living in Okinawa, Japan in 1993

The tech who maintained the computers there was installing it and playing it and he let me play as well. I remember he was going to connect two of the computers via null modem so we could both play but he wasn't able to get it to work. After he left I figured out how to bypass the demo software and I created a alt 255 directory and hid the game in there. I also created a backup by renaming the files as other files.

The only way I could play Doom was on the exchange computer since I only had a 286 at home and no one close had a decent enough computer.

I remember one time I loaded the Barney mod and a kid saw it while I was playing and started crying. heh.

Since I didn't have a decent computer I was able to get Doom for the SNES but it blew chunks so I didn't play much of that. Even then I was a PC snob.
http://doom.wikia.com/wiki/Super_NES

I was blown away by Doom but I do wonder how different my impression would have been if I hadn't already played Wolfenstein 3D.