To my knowledge, not many arcade classics came out for the PC-8001. More than none, but not many. PC-8001mkII had a few more, but for the first generation it's pretty rare. Dig Dug is one of them. It doesn't appear to me to try to do anything clever to make an impactful gaming experience, it just sort of takes the limitations of the PC-8001 and makes an approximation of Dig Dug based around them. Guess that explains the lack of competition at the end of the auction!