This breadboard simulation is simple and easy to code. All of the code is open to view on the 123D Circuits app page and can also run the simulation through the simulator option. This projects could also be used to manipulate christmas lights and tweaked to the users preference. visit http://123d.circuits.io/circuits/97734-led-fun
to see the circuit in action.
The circuit uses the arduino to ground each LED at a increment to make the effect that the lights are chasing each other. I also used the digital signal to control the second row of LEDs by inverting them to the end of the LED row on the other side.
I attached a video to see the circuit in action!