Install Processing
Make sure you have Processing installed on your system. You can download it from the official Processing website: https://processing.org/download/
Install Python Mode
After installing Processing, open it and go to the "Sketch" menu. Select "Import Library" -> "Add Library...". In the Library Manager, search for "Python Mode" and install it.
Download the Sketch
Once Python Mode is installed, you can download the files in this repository, make sure you download the whole folder with the name of the game.
Open the .pyde file with processing
Get into the folder, open the .pyde file with processing.
Run the Sketch
Click the "Run" button in the Processing IDE to execute the sketch. Alternatively, you can press the "Play" button in the top-left corner of the IDE.
Learn more about Processing https://py.processing.org/tutorials/gettingstarted/