BUILD

Windows:
Built in Windows with MSYS2.

These are more or less the instructions I followed from a post in Stack Exchange to install MSYS2. It wasn't crystal clear and I didn't take good notes as I was doing this, but this will get you at least really close, if not all the way, to having an MSYS2 install for building the source:

Download and run the msys2 installer.

pacman -Sy pacman
[close and re-open]

pacman -Syu
[close and re-open]

pacman -Su [close and re-open???]

pacman -S mingw-w64-x86_64-gcc
pacman -S mingw-w64-x86_64-toolchain
??? probably don't do this one: pacman -S mingw-w64-x86_64-SDL
pacman -S mingw-w64-x86_64-SDL2
pacman -S mingw-w64-x86_64-SDL2_image
pacman -S mingw-w64-x86_64-SDL2_ttf
pacman -S make

Once it's all installed, open a MinGW64 command prompt, cd to where No Quarter is (the root of your C: drive is /c in mingw), then cd to the "src" directory. type make -f makefile.mingw This will compile, and also place a copy of nq.exe in the parent folder (there is no separate "install" target) ready to go.

Linux:
Not much to say. I had one library missing, but I forgot what it was. Whatever it was, it was easy enough to install from Ubuntu's repos. Make sure to comment out the #define NQ_WINDOWS directive and un-comment the #define NQ_LINUX directive in the source.