XYZ wrote:I haven't been able to change the ruleset to "fcweb". I only get the message that the game has already started and that it's not possible anymore. How can I change it?
You wouldn't have that ruleset available on (desktop) freeciv even if it allowed to change ruleset of a running game. So I recommend keeping that change out of "master copy" of the scenario to keep it usable on freeciv, and only apply the change when ever porting the scenario to freeciv-web.
In practice you have to do that change manually, by editing (uncompressed) scenario file in text editor.