This is a mirror of sdlquake, originally obtained from the SDL website.
On top of the original sources, patches are applied to support ToaruOS's audio layer and patch out a handful of things that made building problematic on ToaruOS in the past.
You probably don't want to build this from source. If you do want to build this from source, you need to build SDL first, and doing that correctly to produce a shared object is not documented.
If you were looking for how to play Quake on ToaruOS, just install it with sudo msk install quake - this package includes the shareware release of the game files.
This is based on the GPLv2 release of the Quake sources. See COPYING for details.