Complete 2 veteran levels, for example, the leftmost and topmost battlefields. Press Left at the map screen, and the battlefield highlighting will disappear. Begin playing to start on the 2-player battlefields.Quick Targeting
Enter the cannon stage and attempt to place a cannon 5 times at a location that will not accept a cannon. The firing stage will start with the crosshairs directly over this location.Clear Old Castle Remains
You may clear old castle wall remnants by shooting them during the cannon stage.