License

FTE is licensed under the terms of the GNU GPLv2, or (at your option) any later version.
The OpenXR and OpenSSL Plugins are additionally subject to the apache2 license, and thus must be licensed under the GPLv3+.
WARNING: Game content is subject to third-party copyrights and licenses, using a GPL-licensed program does not mean you can pirate Quake/etc. They are separate works.

GPL2/GPLv3 compatible dependancies:

zlib (in-engine): ZLib License
libpng (in-engine): ZLib-Like
libjpeg (in-engine): BSD-Like
libopus (in-engine): BSD
libspeex (in-engine): BSD License
libvorbis/file (in-engine): BSD-Like
libbzip2 (in-engine): Modified Zlib
libsdl2 (in-engine): ZLib License
xz (in-engine): Public Domain
freetype (in-engine): Either FreeType/GPLv3, or GPLv2+
ffmpeg (via plugin): LGPLv2.1
libcef (via plugin): BSD
ODE (via plugin): LGPLv2.1 or BSD-Like
Bullet (via plugin): ZLib License

GPLv3 compatible dependancies:

OpenXR SDK (via plugin): apache2
OpenSSL-3 (via plugin): apache2