Kingdom Under Fire was actually the main inspiration for the game. The battles in that game are amazing.
Too bad Kingdom Under Fire 2 is so different from the original XBox games. I wonder why they decided to make the game a MMO instead of focusing on a single player experience. It is definitely in development hell and will probably never be released.
In response to some of your suggestions:
"Demolish building don't give you back some resources"
-This is a good idea. I will look into it.
"If you lose Royal Guards you cant rebuild them"
-This is by design. They function like units from items (0 upkeep). Makes the player want to keep them alive. Although you can reinforce them if you have the resources.
"The hero should level UP like all the other units"
-Heroes hired from the Tavern can level up. The Lord cannot level up.
"Why I can't sell in the market extra stuff like armors and weapons, or buy needed resources?"
-I may add the ability to sell additional types of resources. I did not include the feature to buy resources as the player can just spam housing to get a very high income and use the gold to buy resources instead of producing them from buildings (makes production buildings redundant).
"Why catapults can shoots while in melee combat?"
-In a old build of the game the catapults could not move or shoot while in combat. In practice I found that this made the catapults useless and a non-threat. Because of this I made it so catapults could move and shoot even while in combat. I will try to find a way to balance the catapults.