Same for me with the HTTPS Everywhere extension. Just click "load unsafe script" and it will work. Note to author, use a protocol-independent script tag, e.g.

Same for me with the HTTPS Everywhere extension. Just click "load unsafe script" and it will work. Note to author, use a protocol-independent script tag, e.g. //github.com/wagnerandrade/old-school-racing/releases/download/0.0.1/old-school-racing.js