Using one of my dad's ancient parallel cables and fooling Windows into thinking it was a LAN connection, which worked well enough, we played for days, until it got kind of tedious. So we then got into the whole modding scene - not creating anything, but downloading and testing the things which were out there. I will never, ever forget Girobot and KQP (Killer Quake Patch).
The Girobot bots were a force to be reckoned with when they didn't get stuck in the terrain. It was KQP which added all kinds of crazy mods/weapons/bot systems to the game that was the real gold. The Vampire Gun left us in stitches every time someone was hit by it, because it basically guaranteed a slow but not too slow death in which the hit player would crumble into little chunks of flesh. I miss the nineties very, very much.