So yeah, there's this mod called Neotokyoo that recently got a patch.
You owe yourself to play it if you have Source SDK. It is easily one of the most engaging Multiplayer FPS Mods out there. Why should you play?
-Stellar art design
-Community known for its unparalleled standard for sportsmanship
-Maps and weapons that will demand the use of tactics and and teamwork to outsmart your opponent
Meh, go to the website, they do a better job describing it.
I will not lie though, this mod is pretty hard, and the skill curve is exponential. But please don't be discouraged. Keep at it, ask questions, make friends. Before you know it you will be one of the magical pros of this magical game. There is no other game that explores the might of a cyberpunk universe as this one does.