It sounds like lemmy.world also had issues upgrading to 0.18.1 rc1. I believe they skipped 0.18.0 because the captcha feature was removed in that version, but readded for 0.18.1. They’re solutions may be helpful, assuming it was similar issues.
CoraQuest is a fun kid-friendly cooperative dungeon crawl that my 6yo and I really enjoy. (Edit): Rereading, I forgot the part about your kid turning five, so this may be a bit advanced.
Outfoxed! (2014) has been mentioned several times and I also recommend it. It’s a cooperative, clue-esque deduction game.
At work: Alpine-based docker containers. Flatcar Container Linux for host VMs.
Personally: Ubuntu Server. Some alpine docker containers.