Nice find with that boxed Mattel Armor Battle. I loved that one when I was a kid.
Zero Wing was an arcade game? I didn't know that. I assumed it was just a console shooter that was ported to/from the Mega Drive and PC Engine CD-ROM. Congratulations on an amazing find! All your base really do belong to you now.
I bought a boxed and complete copy of Swords and Serpents for the Intellivision for $5. I've only ever had a loose cart before, now I can finally figure out how to play it since I have instructions and overlays.