MusicThe background music is in fact the catchy Popcorn by Gershon Kingsley from 1972. The other song featured, when you "power up", is the famous 4th movement from The William Tell Overture, otherwise known as The Lone Ranger Song. The familiar ditty when you die is in fact an old Catholic hymn entitled Pray for the Dead.
ReceptionDigger is the most widely recognized (and popular) of all Windmill Software titles; many patches, utilities, and even a complete disassembly and rewrite have been made. This may be due to the fact that Digger has a more complex structure than Windmill's other games which were merely variants of simpler concepts (Joust, Centipede, Galaxian, etc.).
Demo versionDigger is one of the four games featured in the "Windmill Software Demo Disk", a rare release circa 1986 which contained playable demos if Conquest, Digger, Rollo And The Brush Brothers, and Styx. The games contained more verbose gaming instructions than the originals, but only the first level(s) could be played. These demos were released into the Public Domain.
Information also contributed by Apogee IV, WizardX