Nichibutsu Arcade Classics 2: Heiankyo Alien

Heiankyo Alien (平安京エイリアン, Heian-kyō Eirian), known as Digger in North America, is a maze video game created by University of Tokyo's Theoretical Science Group (TSG) in 1979. The game was originally developed and released as a personal computer game in 1979, and was then published by Denki Onkyō Corporation as an arcade game in November 1979. In 1980, the arcade game was released in North America as Digger by Sega-Gremlin, with minor changes in appearance. The game was a commercial success in Japan, where it was among the top ten highest-grossing arcade games of 1979 and 1980. The game has been ported to several other gaming systems since its original release.