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

I use the same approach in regular gameplay to save turns. For example, in a battle for a Rampart, it's often not beneficial to split up the Centaurs; 4-5 units are usually enough, and the rest just get in the way. In general, even in War of the Titans, I conduct more than half of the battles without splitting my stacks.