The fugue is a musical form where two or more instruments each play the same melody, alternating or at the same time. The word "fugue" comes from the latin word "to chase", and that actually describes the form of the composition perfectly - the various instruments chasing each other around the entire score.
We've seen this musical form here before, Bach's "Little" Fugue and his more famous Toccata and Fugue. Bach was by no means the only composer who wrote these - we've also seen Adam Falkenhagen's Fugue in A Major here.
But all you really need is a tune to make a fugue. Vincent Lo took the (once famous, now forgotten) ring tone from Nokia cell phones to create his take on the form. For some reason, this made me grin.