"Curiosity killed the cat"? It's one of my two remaining "event" achievements along with "The bigger they are".
I only learned what to do after looking at someone else (a beginner)'s achievements (i thought Steam would spoiler achievements i didn't have, but apparently not). I had already
waited a good amount of time in the Scrapyard in the past (and destroyed the neutral bots as they arrived), and left when no new units arrived for around three hundred turns.
Because of that, i there was nothing more, and never would've figured it out on my own, unless i missed a hint somewhere?