Точно това е формулата, само че има малка грешка - не е (days-10), а (days+10).
Едно време имаше един супер сайт - astralwizard.com, който изчезна. Добре че съм го свалил целия навремето.

Ето по-подробно:

Staight from Maranthea on the message board, this is the formula to calculate scores in HOMM 3 stand-alone scenarios.



Base Score = 200 - (days+10)/(Towns+5) + 25 (if you defeated all enemies) + 25 (if you got the grail)
Final Score = (Base Score)(Difficulty level map was played on)


In English, it gives us this:

1. Start with a score of 200

2. Add 25 points if you beat all enemies

3. Add another 25 points if you get the grail

4. Subtract an inefficiency penalty: The number of days to complete - 10, divided by the number of towns on the map plus 5 (in other words, the more towns to beat, the more time you can take without being majorly penalized)
This will give you a score up to 250.

Multiply this by the difficulty rating (0.8, 1, 1.3, 1.6 or 2) to get final score. Theoretically, the max score would be 500 (defeat any map in 10 days on impossible while killing all enemies and getting the grail). Map difficulty (easy normal hard, expert) seems to be irrelevant.
(source: Maranthea on the 3DO Message Board and submitted here by Quebec Dragon and Angela )