Berserker@Quake2 mod
www.moddb.com
This is a graphical mod developed by a russian modder called Berserker. It's an active project since 2008. The mods purpose is to enchange Quake2's graphics.

This one requires a little bit of dialing in of the settings, particularly the lighting and bump mapping. But after you do that, it’s a pretty fun way to revisit Quake II.

I played through the SP and mission pack campaigns a couple years ago using this source port, and had a really good time.