I mostly use the guard calculator, and then probably the library website (physics department). If all of this were in an app, it would be great.
Regarding the lobby rating and other things, I don't think the rating itself deserves to be displayed yet. We need statistics on templates, heroes, castles, and so on. Then it would be interesting to study the rating, but just looking at the numbers is not that interesting.
I think that collecting such data would require either the player to enter this data after the game through the app, or integration with Hota and their service.
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Obviously, the most interesting thing is the interactivity, as well as possible support for the Polish language.