Awesome! Thanks for considering my suggestions!
I do believe that with "Mouse mode" the user would also benefit with the game showing a visual cursor, cause when doing quick moves, I find if not showing the mouse cursor with just changing the active block indicator with an invisible cursor would give lots of room for miss-clicks (I have seen this happen before with other games and had to revert back to joystick). So in short, please do consider a "visible" cursor if you add this feature.
Yeah a vertical mirror, a horizontal mirror (one or the other, or both in random), and if the map is square; a 90° rotation (or random case degrees of either 0, 90, 180, 270) should be enough to at least delay the opponent in copying your moves with confidence.
This will be the most complete MineSweeper game ever which the Amiga community will be proud to have!!
Great work!