I'm not so sure of the Ethics of completely stealing Kings Bounty and passing it off as your own, just by changing that skin. The original game is over 15 years old now.
The difficulty setting needs to change. The first two chapters are too easy, the third is way too hard, and then the rest just get easier and easier. It starts to loose it's charm. Still a 4/5 though, would be a 5 if it was a bit more challenging.