Lovely idea and implementation. Two thoughts for improving further.
1. Allow additionally for SPACE BAR and/or LEFT-CLICK (perhaps an enlarged area bottom left where it says FLAME ON / OFF), to control the flame. Those will work with the majority of assistive technology for switch users. it would also help eye-gaze users too.
2. The Windows download doesn't seem to have a full-screen option. It would be good to allow the user to toggle between windowed/full-screen via an on-screen option at the menu screen perhaps.