I think I figured it out. This is probably a boss fight involving a mega UFO that has smaller UFOs. I assume you need to try to defeat all of them to beat the mega UFO.
I think that's what we had in mind, yes. Either way, I don't think it's possible to beat all UFOS in the game's current state, pretty sure there's no end sequence or anything that would respond to your progress. Still, I think it's kinda neat, that's why I thought it deserved to be at least published