In terms of narrative, this is a simple story of a mother and son trying to escape a disaster together, as the sun is blotted out and their city plunged into darkness. The narrative value though is greatly helped by how well the delivery works, and how cleverly done it all is. I don't know all the technical details, but essentially the city was built in polystyrene, and used as a reference for computer animation of the characters. This computer animation was then projected onto the real world model and filmed as it played out. This mix of real and light gives the film a unique feel, but also allows for a very expressive play on a shadow puppet show.
The story is simple but does have heart. Were it a straight animation then probably it would engage less, but the animation style adds to the feeling of the characters, while also impressing in how precise much of it is. Too often, interesting delivery ideas are clearly in search of something to deliver with them, but in this case it manages both in a short and engaging film.