When you are designing a side-scrolling endless runner, there are two primary design approaches. Some will use a physics engine like Box2D or Chipmunk to help control all of the object interactions. We will be taking the other approach by building our own lightweight physics engine for the game. All of our ground will use square tiles, so we can easily identify the surfaces our hero can walk on safely. We will build sensors on the top of all walkable surfaces, as well as building sensors underneath each of our walking characters (hero and enemies). The hero will be in a fixed x coordinate on the screen, and the world will scroll past the hero. We will have two types of enemies: flying and walking. Both will have similar behavior, but the walkers will have the sensors we mentioned to allow them to walk back and forth on their platforms. Enemies will not be allowed to walk off the platforms to their death. We will also implement a two level endless parallax background from scratch...