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

actually, I came up with a useful feature for the general transfer buttons:
you select a stack with a click, click the button - a single unit remains in the selected stack, and the rest of the army is transferred.
this is a keyboard-free transfer method with the option to select a single unit.
I, as a non-competitive player, like this.
And I'll definitely remove the "intelligence" of leaving a single unit – I'll make it so that the weakest unit is left without any selection.