I just got a new idea for the game-- Battles at your house! There will be a new NPC or Object in your house that you can talk to and they will give you a list of a new thing: "Invasions!"
The NPC/Object will have a list of current invasions you can do, and says the rank of the enemies on the side. Click on one, and if you successfully defeat all enemies in your home, you get a reward. Experience, Gold, items....and yeah.
With this there will also be a new type of housing items: Battle Items. Things such as golems and minions to help you fight off enemies. Forts, defense walls, etc.