GTA: Royal Offense
Evil forces are at work as the castle is under siege by hordes of monsters. The king don't want to see his castle to fall in the hands of the master, so he sent his best men to the sight to protect his subjects. You need to send men to defeat the monster harassing the lands. But, you need money to send in more men, so focus on your economy first before battling. The game gets harder and harder as you make some progress. You need to upgrade your men, so you can ward off the incoming threat.