A mandelbrot set viewer I made to play with SDL and complex numbers. The only requirement is libSDL (version 1, not 2).
fractal/ $ make
gcc -I/usr/local/include/SDL -D_GNU_SOURCE=1 -D_THREAD_SAFE -L/usr/local/lib -lSDLmain -lSDL -Wl,-framework,Cocoa -o frac frac.c
fractal/ $ ./frac