I'm not inspired to give it a name yet, and I think it's still unfinished, because there are some bugs I figured out that I haven't found a way to fix yet.
It has new features, all Q2 weapons, some Q2 monsters, 4 new monsters and AI enhancements. Source code is included as well.
The file has 6.6 mb. Enjoy.

EDIT: I just figured out a bug. Monsters sometimes plays a gasp sound when seeing an enemy.