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

There is another, simpler way. I've suggested it 100500 or 100600 times, but it hasn't been implemented.
The idea is this: when generating a map, each player is asked to enter a password. When loading a save, each player is required to enter a password. If any part of the password is not entered, the save will not load. That's it. No other anti-cheat measures are needed.