anti-Necropolis faction

and the term "average game length" is too vague.

That's exactly why I asked to specify the game length in weeks.
Because measuring the game length in terms of the main hero's level is not correct, in my opinion.

Because on some maps, the main hero reaches level 20+ by the end of the 3rd week, and on some, it's not even certain that it will be possible by the 5th week.