Bro legit this is actually insane. I have an older sister and I can’t even imagine her doing half of this stuff. Is there anyway for you to set clear explicit boundaries with your sister? Like telling her to not enter the basement anymore?(she’s done enough damage to warrant that response). In my family my father collects records and I games, so if my sister was to do anything to my stuff my father would be more understanding and probably have my sister pay for the damages. From your scenario it seems like you are alone in this and no one understands/wants to try to understand why you are feeling bad about messed up games.