This assumes that your systen already has Homebrew (https://brew.sh/).
$ brew install sdl2 sdl2_image sdl2_ttf jsoncpp
$ g++ src/**/*.cc \
-I./include \
-o bin/game \
-lSDL2 \
-lSDL2_image \
-lSDL2_ttf \
-ljsoncpp \
-stdlib=libc++ \
-std=gnu++2a \
-m64 -O3 -Wall
$ make
$ bin/game