As you might guess, this is a reference to the War of the Worlds by H.G. Wells. I have always loved his work, and War of the Worlds was my very first book as a child.
The development of the video took about 10-12 hours - approximately equally for artwork (Photoshop) and animation (After Effects).
I spent several hours on the 2d-smoke effect - I couldn't find a single tutorial suitable for the style on YouTube, so I had to figure out how to create such smoke in stock AE without plugins and scripts.