Because it was. I was playing ton of video game at that time and the mod community around half life was really fun and creative.

Science and Industry was a fun mod as well. But yeah I also remember CS ad being at another level right away.

Do you remember Wanted? The wild west one? Good craic.

Then there's Ricochet.. :')

The Natural Selection half life mod, and the standalone NS2 are still the best (maybe only?) asymmetric shooter/RTS hybrids I've played.

I did not until now haha! But now I do.

Someone else mentioned “natural selection” as well