Hi Michyo
You can start the project just by clicking on the .html file.
On the top right you can select import and then find the .fistf file from your pc.
Files are downloadable here: https://jonathanneels.itch.io/combolade
The app.py is rudimentary now, you can do a network "combat", but not refined.
The other (offline) modes should bring you some joy, I hope.
Good luck, keep me posted!
Kind regards
Fumetsujo