Install python 2.7 via brew, gzip, anaconda etc.
Install packages:
curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python get-pip.py
pip install WebOb
pip install Paste
pip install webapp2
pip install Jinja2
Go to level folder e.g. level2 and run .py file:
cd level2/
python level2.py
Check game at http://127.0.0.1:8080
Origin source: https://xss-game.appspot.com