As far as I know, this is the only traditional playset featuring Godzilla produced by an American toy company in the ’70s and ’80s, and it’s interesting for a number of reasons (other than the one just stated).
First, it marks the only appearance of Tricephalon, an obvious attempt to mimic King Ghidorah without paying for the license. The box art depicts a mecha-hydra, anticipating both Mecha-King Ghidorah from Godzilla vs. King Ghidorah (1991) and Hyper Mecha-King Ghidorah from a 1997 Japanese TV series called Godzilla Island. (There was also a three-headed robotic dragon in the NES game Magmax, first released in 1986)
Second, the destroyer in the set is “missile-firing” (see warning on box) at a time when toys firing projectiles were being hastily recalled.
Third, the box artist is likely Earl Norem, who painted the cover for HG’s Buck Rogers Galactic Play Set from the same year. It looks very much like Norem’s color scheme and style. An expanded version of the playset art was used for a large Godzilla jigsaw puzzle, also issued by HG, also from 1979. The detailed human faces on the lower panel further convince me that Norem is the artist.
Check out The Sphinx (who makes the same point about Tricephalon anticipating Mecha-King Ghidorah) for close-ups of the Godzilla and Tricephalon molds, and for a listing of the set’s full contents.
(Images via Materialist Zen and The Sphinx)
2 Warps to Neptune 
So very cool!
Had it as a kid till LaValley ruined my life.
You’re totally right that it’s Norem. He did a lot of work for HG at the time, last year I helped him sell his original Alien puzzle art from the same period.
That Alien puzzle is bloody fantastic, as is this one. I hope he got a bundle for the original art. And thanks for helping him! If there’s anything I can advertise here, let me know.