On linux, you need to install tkinter:
sudo apt-get install python3-tk
sudo apt-get install python3-opengl

On mac, install pygame like this:

brew install python3

# Not sure if this is actually needed
brew install sdl sdl_image sdl_mixer sdl_ttf smpeg portmidi

pip3 install pygame
pip3 install pyobjc
pip3 install PyOpenGL PyOpenGL_accelerate
# PyOpenGL_accelerate is needed on OSX, not sure if it's needed on
# other platforms

On Windows, install python3 (which should install pip) and then:

pip install pygame
pip install pyopengl

Run the game with:
python3 game.py