Base Defense is a single/cooperative modification based on horde-style and RPG systems. It's awesome, you should try it ;)
Just gameplay video of the latest version available.
Released 20th January 2016.
Track in video: Xenogenocide - Scintillation.
Tracks don't work for me o_O
MP3 volume must be set in settings.
Also music doesn't works under Xash3D.
Thanks for telling me that now I can fix my problems before I play.