Space-shooter.c: cross-platform, top-down 2D space shooter written in C
The title led me to think it might be a single file, but still this is good stuff.You could probably make it a single file if you used the wonderfully obscure XPM image format for your sprites and assets.  It is both a C source fragment and an image format in one! https://en.wikipedia.org/wiki/X_PixMap