Grow your castle to protect your citizens from growing numbers of invaders.

Strategically build walls by placing them along tile borders during the build phase.
: Gain soldiers by enclosing houses within your walls : Make ballista towers by enclosing a tile with walls

Watch your defenses fend off the invaders. : Invaders will tear down your walls and destroy your houses : If you survive the round and your defenses kill the last invader, another Build Phase will begin.

Kill all of the invaders before they destroy all of your houses.