While I can see that you put a lot of work into the game, I'm just not feeling that strategic element in for this type of game. It feels like the best option is just to sit back and build up defenses, then rush with all 3 of your heroes and a bunch of long distance siege weapons. It's also pretty apparent that the PC controlled side is not bound to the same gold and experience buildup rule that the player is bound to.
The game is also very slow, which makes the game incredibly boring. You might want to add a speed button to hurry things up. Also, adding a forward button, and a retreat button, well help the player feel like they have some control over their warriors, instead of just sending them to their slaughter.