While most seemed to prefer Counter-strike, my childhood gaming was dominated by an Unreal Tournament mod called Tac Ops. While the games looked similar, the mechanics felt very different than Counter-strike. It was a much faster-paced game.
There were a ton of servers with wacky mods. I spent a ton of time on the low-grav servers. There were also some that made the top-scoring player huge. Those odd game modes were a blast.
EDIT: Also looks like people are still playing!
https://www.gog.com/dreamlist/game/tactical-ops-assault-on-t...