story identification - Searching for video game like Xevious but with more interesting bosses

I am trying to find an arcade game that I saw in the 1980s that made a strong impression on my with the innovative appearance of its bosses. It was a top-scrolling shoot-'em-up,

I saw it somewhere in the range of 1985 to 1989 (most likely in 1986), at Skate Palace in Salem, Oregon. Seen from a distance, at first I thought it was Xevious, as I remember it having a similar color scheme (with lots of greens and earth tones), and I saw a player defeat a boss that looked a lot like the Andor Genesis mother ship bosses from Xevious.

As I remember it, the boss had a similar shape, square but with cut corners to make it an octogon. However, it may also have had an extended arm attached, unlike the Xevious boss shown above. It also shot more interesting looking missles, shaped like boomerangs, unlike the small and large spheres in Xevious.

The first boss down, the player I was watching made it through another stage, to face off against another monster alien craft, which was the one that really caught my attention. It was like a gigantic silver or gray metal insect. I remember it as being closest to a grasshopper or locust, but it might have a different bug. Moreover, it shot interesting missiles as well, little metal fists (extending back a bit past the wrist) that shot forward, propelled by rocket flames. I think the player died against his enemy, and I did not see any more.

Later, as I got to know Xevious better (and had multiple friends who actually made it all the way through that game), I recognized that this had not, in fact been the same game. Over the years, I have actually played quite a few (mostly emulated, through the MAME library—which I have looked over, albeit nonsystematically) Xevious-style arcade games in an effort to find this one again. However, thinking about it now, this was probably not the right approach. There are plenty of "Xevious clones" out there, but what distinguished them from other vertical shoot-'em-ups was that they had both turrets for firing at enemies in the air and bombs for hitting the ground. In fact, there is no reason to believe that the game I saw had Xevious's innovative bombing feature; I probably just associated what I was seeing with Xevious because of its similar graphics style and color palette.