Castle story allows you to create complex structures using bricks. Castle Story Bricks are the basic building material within the game. Cubes are easier to manipulate which is why bricks are used instead.
Cubes would also only be able to be stacked on top of each other. Building castles with 1×2 bricks will hold each other up if you stack and build them correctly by alternating them. The key to building with bricks in Castle Story is how well you alternate the bricks. You may be faced with challenging circumstances which is where your true brick building skills will come into play.