Off the top of my head, I know Heretic and Doom have custom models and textures from the Doomsday guys, I know there is a high res quake texture pack, there is a high res Jedi Knight pack, but none of those include levels / models / sound / etc, so they are all addons to the base games.
Freedoom is the only total conversion of a FOSS'd major game engine with FOSS assets that is actually playable that I know of. If anyone knows another, let me know, I'd love to play them.
Off the top of my head, I know Heretic and Doom have custom models and textures from the Doomsday guys, I know there is a high res quake texture pack, there is a high res Jedi Knight pack, but none of those include levels / models / sound / etc, so they are all addons to the base games.
Freedoom is the only total conversion of a FOSS'd major game engine with FOSS assets that is actually playable that I know of. If anyone knows another, let me know, I'd love to play them.