King's Bounty: The Legend

What does difficulty have to do with it?

It only matters in the sense that you might not be able to complete the game on an impossible difficulty. What difficulties could there be on normal? You run up to the bots, hit them on the head, and they die.
On impossible, you have to think: what to cast and in what order, when to wait, where to move, and how to counterattack.
For me, the interest lies in doing what seemed impossible yesterday. It might take a month to complete. The interest isn't in beating all the bots in two days; that can actually get tiring.