RPG based on Might and Magic.

There's no need to worry that those unfamiliar with the lore will be at a disadvantage. Familiar events will still occur from time to time. Familiar characters will behave accordingly. And, of course, there will be GM assistance.
In my opinion, there's no need to create overly complex mechanics. It would be good to borrow the role-playing system from Might and Magic. It seems to me that it is optimal.