I'm not sure having the person you were sent to rescue get their finger cut off counts as success. There have to be ways to 'fail' that don't cause the game to grind to a halt or end in a TPK - that means broadening your understanding of what counts as failure.
Finger cut off? Huh?
I never said anything about TPKs or the game grinding to a halt. I don't want a game where everything always succeeds. If at first you don't succeed either there will be other options or perhaps you need to rethink your entire approach and/or goals.