Let me start by saying: “I’m not a lawyer, but…”
By uploading Ravioli Burglar Simulator that is exactly what you’ve done, The_Man_Official. You cannot just take someone’s original work as a whole and publish it wherever you feel like. If you’re not licensed by the original creator that’s a form of copyright offence. If you want to know the exact specifics, talk to a specialized lawyer.
As for 18 Aliens looking at another person’s code to fix an issue with their own game: I think morally that’s fair game. If I understand them correctly they didn’t nick an entire mechanic but rather looked at how a rather basic mechanic worked elsewhere and made corrections to their own code based on that knowledge. Also: It would be very hard to prove any of what they did in a court of law - while your DMCA claim worthy action is already in a lot of logs as well as possibly on archive.org.
Look… I can maybe not say what exactly happened between the two of you. But I can tell that if both of you stay on the course you are currently on, it will end in tears for one of you - well, at least one of you. Probably the one who basically already admitted to breaching international law. Publicly.
But I’m sure that’s all just my opinion and it will all work out perfectly fine for you…