I've actually been playing a bunch of older games this past month, but nothing jumped out at me as being particularly interesting, so I'll stick with an old standby...According to Wikipedia, this is referred to as the Galaxian flagship, or Galboss. I don't know who came up with that. It's hard to trust Wikipedia sometimes. I remember playing Galaxian a lot as a kid, and never being very good. This was in my "get as far as possible without dying" phase, which was not broken until college, when I finally decided to start going for high scores. I also don't know why I preferred this game over Galaga, which now is obvious as the superior game. Maybe I liked the look of the ships in this one better, or it seemed less complicated.
Nevertheless, I didn't know that if you saved the boss for last, if he flew off the screen, he'd actually go away and reappear on the next wave. so you could theoretically have up to 4 of these ships on the top row, rather than the regular two. I really don't know the point of that, because they're hard enough to kill when they're all coming at you at the same time.
This sprite also appears in Dig Dug as a bonus item, and a bunch of Pac Man games, including the original one, as a "fruit." It is obviously a Namco thing, much like the Capcom Yashici. What? You haven't heard of that one? Maybe another time, dear readers....
