At the time, I worked for a company with a large training room full of computers. The room had locking doors, and a small, narrow window in only one door. We made a cardboard cutout that fit into that window perfectly, and painted it flat black. If you put it in the inside of the window, it appeared as if the room was empty and dark. We called it the "beat-down screen".
We loaded up the UT demo on every machine in that room, and used to get a bunch of like-minded gamers to come down at the end of the work day and we'd play the three demo maps for hours. We eventually added Half-Life deathmatch (I loved the snark pit map) and Counterstrike. None of those machines had discrete video cards, so we had to run in software rendering mode on all games, at something ridiculous like 320x200, but it was glorious.
Good times.