All this research was done by Frogcuda of SFKosmo, which I’ve linked for years, so I don’t feel bad about stealing it blog-style for a post. Also, it was only previously on forums, so wouldn’t be properly chronicled. So here goes – First, there was this interview with Treasure’s Yaiman about Astro Boy. Some of it talks about Bangai-O though, and one part of the interview translates to: “Bangaio started off as a remake of an X1 game called “**-****”, but then I started to mix in Anime influences from Edeon, Macross and Layzner, and pretty soon it was didn’t resemble the original, and so its being a remake became 120% a bluff/lie.“
After some research, someone found that the game was called Hover Attack. In fact, as you can imagine, this was known in Japan long before it was discovered here, since the X1 was released there and all. Find the 10/22/2000 entry on that page for the post (which, by the way, basically says they look similar, but that Bangai-O is rather a large leap from Hover Attack). Still, neat to see the origins of this game. Hover Attack was made by Compac – you can find the cover here.