I think there was a stable cooperative strategy for the lowest unique bid game: One player bids 5, but the others bid 1, 1, 2, and 2. That way if one of the players who were supposed to bid 1 or 2 defect, they’re only handing the money to someone else (and simultaneously reducing it), so there’s no incentive to defect.,(reply>), @Jakub Supeł Conspiring is difficult when you are all around the same table.,(reply>), But a pair of people may also conspire to defect. If you and me are supposed to pick 1, I can promise to pick a 2 instead if you promise to pick a 4 and pay me half of your winnings.,(reply>), ​@OMGclueless Only every good strategy, and they were a bit slow at figuring out the good strategies.,(reply>), @J B That's true of every strategy in this game though.,(reply>), @OMGclueless Then its is known who the defector is and that can be played around for the rest of the game, also people are far more likely to cheat someone out of money if that person can't know for sure it was them.