How could they not tell that was a trap room from the get go. The room was far too big for a regular chest room. Was this their first RPG? Surprised the chest wasn't a mimic that bit your head off.
Though if I was in that situation I'd do my "stand in the doorway and let the tiles come to you" tactic commonly used in Zelda games and just swing my sword. It avoids the whole being stabbed in the back issue that they all suffered from. And as I said earlier, use a door stop.
Or maybe you shouldn't go off on your own without the leader. Stupidity killed them. I only felt sorry for the girl since she got dragged into this mess. The other three deserved it. They get no sympathy from me.
The leader could have at least left one key behind... Wonder if his body found found later by another party.
Well he made for a good
bail out/nope gif. Or if you want the full thing
here it is.