HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

the space above the options is occupied by a button to hide/show the chat.

The ability to change various options within the game itself was, of course, planned from the beginning, but a convenient, well-designed graphical interface that doesn't look like a patchwork on a tuxedo (hello, WoG) is not easy or quick to create.

Added after 15 hours and 3 minutes
I'm currently testing the function - replay of your own turn (it's convenient to watch and analyze saves).

How to implement it: should the "replay opponent's turn" button show not only the opponent's turn but also your own turn (as it does now in online mode while waiting for your turn)? Or should a replay of your own turn be assigned to a separate button/key???

The first option is the easiest to implement.