Thanks to:

ID Software
Valve LLC

Crazy Russian for HL-Style menu buttons code and animation
adamix for scrollbars code in menu
HAWK for translate features.txt on english

Xash3D using some parts of:

Quake 1 (Id Software)
Quake 2 (Id Software)
Quake 3 (Id Software)
Half-Life (Valve Software)
Darkplaces (Darkplaces Team)
Quake 2 Evolved (Team Blur)
AVIKit (by randomnine)