This QuakeWorld-based engine powered some of the most critically acclaimed engine's of it's day, like Half-Life, Counter-Strike, Day of Defeat, and many more.

Loulimi says

10/10 - Agree (4) Disagree

One of the best engines. Created for modding, it gave an variety of famous games like Counter-Strike, Day of Defeat and Team Fortress.

Today, unfortunately, its community and its modding scene is still unknown, mainly bbecause scattered in a lot of small websites. I think we should create a facebook group to gather this community. The content can be uploaded on ModDB, on a wiki, and a lot of other things. It just has to be well organized.

We have already that:
Store.steampowered.com
Steamcommunity.com
Half-lifecreations.com

And a lot of other websites.