Great game, and I have some ideas and problems for you.
1. I can't delete units, even when selected. I am on a Mac OS.
2. Add enterable houses like another comment said, and make a village defense/assault mode where if all houses are destroyed, you lose/win.
3. I think an axe + shield guy would be good, and make the shield round like a viking if you add this.
4. Defense siege where you defend the king.
5. Controls editing, my mouse doesn't let me right and left click at the same time because it is terrible, and I can't throw things because of it. Maybe add an option to make it toggle with right click.
Keep up the good work mate!