How to win Squid Game's rock, paper, scissors minus one

Season 2 of Netflix’s Squid Game is out and they have a twist on a classic game. What's the best way to play rock, paper, scissors, minus one?

0:00 rules
1:54 example
3:04 randomizing
7:40 solution
12:16 best strategy

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[Simoss]

The best strategy is to not have a psychopath in the room

[solandri]

For those new to probability, this introduces an important concept. In recurring games, sometimes the optimal solution isn't one strategy over another. Sometimes the optimal solution is to play one strategy part of the time, and another strategy the rest of the time. With the ratio of how often you (randomly) pick between the two strategies being key.

[RyeedAglan]

When I was a kid, I used to play this with my sister. According to my dad, I played two rocks, and she played two papers.

[woody]

Always useful being able to calculate nash equilibria in your head.

[Vengemann]

Aint no way we got an Update to Rock paper scissors .. We need Rock Paper scissors 2 before GTA -6 Now

[bcsiu]

This video reminds me the Games & Strategic Thinking class I have taken in university. Those pay-off matrices are so nice...

[michaelribeiro]

This is the best strategy for this matchup.

[hentsuj]

Nash equilibrium is not the most optimal strategy. In a zero sum game it just means that player 2 cannot take advantage of your strategy. This is the most optimal strategy if player 2 plays the most optimally against you. However if player 2's strategy is not the nash equilibrium, player 1 can take advantage of player 2's strategy and have an even better payout.

[michaelsparks]

The scene from the show is actually a great demonstration of Theory-vs-Practical. In those characters' scene, the goal is not "win the game", it's "don't lose" (and a tie is not a loss) so the "correct" strategy is actually for both characters to collude and only throw RR each round. They will only ever tie after minus-one, and RR requires the least repeated effort from each player (as your hands are already clenched before throwing R P or S, so you just have to shake your arms before "shoot") letting them conserve more energy and delay as long as possible.
If the badguy really wants to force the outcome where he shoots one of them (and he doesn't just pick either player arbitrarily out of boredom), he'd need to do something else like blindfold them to reduce their ability to strategize. If blinded before starting, they wouldn't immediately know if they picked the right matching pair to each throw for infinite ties. If blinded later and if they begin throwing mismatched signals as exhaustion sets in, they wouldn't be able to read or signal which of their options would produce a tie (ex. 1 throws PR, 2 throws PS, they wouldn't be able to see this and both choose P vs P after minus-one). Without removing some agency from each player, his game would never actually end.

[johnt]

The more interesting question is how you're supposed to "randomize" according to a particular probability.

I know poker players have thier own methods to introduce variance in their play, but they also never reveal how they do this.

[leedanilek]

One important thing to note: if players prefer a tie over winning or losing, they can always force a tie. Like, for example, if you're playing with your friend and a psychopath will shoot the loser.

[Trummler_AKSEP]

The best trategy to both survive as long as possible is to always force a tie

[josephkylerogan]

Great video! Like other commenters, though, I'd love to see the solution for the game if the goal is not to win, but rather to guarantee a tie, like it is in the show. (In the show, it seems like they do actually settle on this strategy, until one of them makes a "mistake" and throws the same symbol on both hands.)

[dr.sleaseball]

this gave me the idea to make a game out of this. in easy difficulty the bot will play completely random, in normal the bot will never play 2 same hands, in hard the bot will use this strategy and in sadistic the bot will see what the player chose first and then cheat some times.

[efan]

Having played this game 40 years ago in Korea, I can conclude that;
1. Never have 2 same items on both hands eg. 2 rocks.
2. This is not a mathematical probability game. It is a psychological game akin to poker.

There is really only 1 situation that needs a deep analysis;
X<Y<Z represent rock, paper and scissors
player A has X+Y, player B has X+Z
A can guaranteed a draw (and possibly win) by playing X
If A plays Y he has possibility of losing
A is called in "domination" or "attack"
B is called in "Passivity" or "Defence"

The key is B's strategy;
If B believes A is playing safe, then must play X
If B believes A is a risk taker, then must mix his play and consider playing Z

[omxky]

3:06 bro introduced inception in squid game from this point 😂

[jacobD]

so, in squid game, if they played the best strategy, but in the last case, they both play 100% of time the same hand, they could have played indefinetely without dying! 0_o (to people who didn't watch, two friends were playing)

[codeyay]

what do you do when you notice your opponent playing sub optimally? If you notice more ties than normal, then on hands where you have positive expected payoff you should increase your switching from ties to possible wins. However, on hands where you do not have positive expected payoff you should only attempt to switch about as much as the other player switches. In squid games where the weight of losing even once means instant loss, people play more protectively so the chance of someone choosing not to tie is much less than 1/3, and so you can exploit this while playing

[toxicenddragon]

It’s all just the prisoner’s dilemma in the end.

[hk-]

If your opponent is male always choose RP and win. Any male can‘t withstand the urge to use R in the first matchup. So with this new game he‘ll either choose RR, RS or RP. If he chooses RR or RS your RP will give you better odds. If he also chooses RP it’s a tie.