Zig Zug is a confused title for the MZ-700 that requires the PCG-700 to display correctly. I think maybe they wanted to call it Zig Zag, but "u" often gets confused for "a" sounds in Japanese. On the other hand, maybe they did want Zig Zug as that just replaces the "D"s in Dig Dug with "Z"s. The katakana actually comes out literally as Jiggu Zaggu but entering "zi" in romaji will produce the katakana for "ji" and there are often disconnects between what the programmer thinks the title is and what the box maker thinks the title is, so intentions are a bit unclear.

In any event, this is clearly a clone of Dig Dug, minus a lot of finesse. It's PCG, they definitely programmed some graphics, but they didn't make any effort with color (they were targeting the MZ-80K and MZ-1200, so I guess you have to forgive them that, as they only had built-in monochrome monitors). The animations are simple and sudden. But it's definitely Dig Dug at heart!