Rock Paper Scissors Lizard Spock: Rules & Strategy Explained

The 5 gestures

All 10 outcomes — with explanations

Each gesture beats exactly two others. Here are all 10 winning relationships and the in-universe explanation for each:

Memory trick: the circle

The easiest way to memorize all 10 outcomes is to picture a five-pointed star (pentagon with diagonals). Write the gestures clockwise around the pentagon: Rock → Spock → Paper → Lizard → Scissors → (back to Rock). The rule: each gesture beats the two gestures immediately to its right in the star pattern.

Alternatively, use the mnemonic: "Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, rock crushes scissors." Repeat it twice and you'll have all 10.

Origin: Sam Kass and The Big Bang Theory

RPSLS was invented by Sam Kass and Karen Bryla in 1998, published on Sam Kass's personal website as a solution to the high tie rate in standard RPS. Kass's explicit goal was to create a version with more outcomes to reduce deadlocks in repeated games between people who know each other's tendencies.

The game existed in relative obscurity for a decade. Then in 2008, The Big Bang Theory Season 2, Episode 8 featured it. Sheldon Cooper explains the rules to Raj in a scene that became one of the show's most-quoted moments. Overnight, RPSLS went from a niche internet curiosity to a globally recognized game variant. Sam Kass was subsequently credited in the show.

Does RPSLS actually reduce ties?

Yes, significantly. In standard RPS with random play, both players choose the same gesture 1 in 3 times (33.3%). In RPSLS with 5 gestures, the tie probability drops to 1 in 5 (20%). In practice it's even lower — most players naturally avoid repeating the same gesture twice in a row, which means their choices are already pseudo-random with low self-repeat probability. Under these conditions, ties in RPSLS occur roughly half as often as in standard RPS.

This is exactly what makes RPSLS useful for its intended purpose: breaking deadlocks between two people who know each other well and tend to "follow" each other's patterns in standard RPS.

Strategy: how Lizard and Spock change the game

Spock is a strong opener

Spock beats Rock and Scissors. Since Rock is the statistically most common first-round gesture (especially among inexperienced players), Spock is a strong opener. Against a player who tends to open with Rock, Spock wins immediately. Paper also beats Spock, so a veteran who anticipates your Spock will punish you — making Spock a strong but not dominant opener.

Lizard targets the "safe" gestures

Many standard RPS players default to Paper when they want to play safely (it beats Rock and doesn't lose to Paper or Scissors in a way that feels "stupid"). In RPSLS, Lizard beats Paper and Spock. Lizard punishes players who default to safe Paper-dominant strategies.

The new dominant pair

In standard RPS, no gesture is dominant. In RPSLS, empirical research on first-round choices suggests that Paper and Spock are chosen slightly more often than the other three by players who have studied the game. This creates a secondary meta where Lizard (which beats both Paper and Spock) becomes undervalued and thus effective against thinking players.

The anti-meta: Rock

Rock is the intuitive default of beginners, making it predictable. In RPSLS it still loses to Paper and Spock — but it still beats Scissors and Lizard. Against players who are thinking about Lizard and Spock, Rock is surprisingly underused and can catch them off guard.