I'm noting all your titles, because soon I'll go to London (where books are waaaaay cheaper than in France!) so I will buy what I'll find!
I remember a French show (a FAKE show) where there was a famous TV celebrity, and she was encouraging random people to do a game: they had to answer questions, and if they were wrong they had the choice to continue and send an electric shock to a man they couldn't see (but he wasn't receiving the shocks, obviously), or to end the game with absolutely no problem, they would'nt be killed or something like that. And just because the girl was saying "it's alright, go on", they ended up sending lethal electric shocks (200 V or so), never thinking it was bad if the man wasn't screaming with suffering anymore.
It's not really a "there will be only one left" story, but that asked the question: "Am I better than these persons, would I have quit the game?"