I'll take a guess, based on your hint: A wine-bottle opener?

Great answer. I don't remember a wine bottle opener in crucial game but there could be one. There might be other similarities in these three episodes.

In Catch and port there's a Rolls Royce but that doesn't tie into your comment about it being integral to Murder Under glass. I'm not sure about Most crucial game.

You hint says "it has nothing to do with the characters", but the only common thread I can think of, is a NEWPHEW being killed by their aunt/uncle.

Your title asks relationship between "Crucial Game, Port, Murder Under Glass", but your question asks "What do Catch Me, Crucial Game, and Port In Any Storm have in common?"

All (4) episodes involve a NEPHEW. Only Port, Game, and Catch-me have the nephew being murdered.

Ed we've waited SIX YEARS now for an answer.... PLEASE ?

A safe?