Snakes and Ladders: Rules and History

The rules

1. The board: a path of 100 squares, numbered back and forth from the bottom-left corner to the top. Several ladders join a lower square to a higher one; several snakes join a higher square to a lower one.
2. Turns: players take turns rolling one die and moving their token that many squares along the path.
3. Ladders and snakes: a token that lands exactly at the foot of a ladder climbs to its top; a token that lands exactly on a snake's head slides to its tail. Passing over a snake or ladder does nothing.
4. Sixes: a six earns another roll, up to three in a row.
5. Captures: landing on a square occupied by another player's token sends that token back to the start.
6. Finishing: by default a token must reach square 100 by an exact roll; a roll that would overshoot is lost and the token stays. The exact finish can be switched off, so that any roll reaching or passing 100 wins.
7. Boards: three layouts take turns from day to day, so the snakes and ladders are not always in the same places.

Where the game came from

The game comes from India, where versions of it have been played for many centuries under names such as Moksha Patam and Gyan Chaupar. The original boards were lessons: ladders stood for virtues (generosity, faith, humility) that lifted a soul toward liberation, and snakes stood for vices (anger, greed, pride) that dragged it back. The number of snakes usually exceeded the number of ladders, to make the point that the path of virtue is harder than the fall.

The game reached England in the late nineteenth century, where the moral labels were kept at first and then gradually dropped, leaving the plain race. In North America a version without snakes, using chutes instead, became the common form. The version here is the classic numbered board with snakes and ladders and no moral captions.

Why a game with no choices is still exciting

Snakes and Ladders is a pure chain of chances: your position next turn depends only on your position now and the die. Mathematicians use it as a textbook example of such chains, and the calculations say something interesting: on a typical board, a single player needs on average somewhere around forty turns to finish, but the spread is huge, and a player far behind can still win because one ladder can leap most of the board and one snake can undo twenty turns of progress. The exact-roll finish adds suspense at the end: a token on 97 waits for a 3, and may wait several turns while the others catch up.

Playing with children

• Let the youngest roll first; there is no first-move advantage worth arguing about.
• Count squares out loud together; the game is a painless way to practise counting to 100.
• Turn the exact finish off if waiting on 97 causes tears.
• Point out the snakes' heads before the game so that a slide is expected rather than a shock.

Playing online

Online, the server rolls the die with cryptographic random numbers and every player's screen shows the same roll, so nobody can shake the phone for a six. A friend who loses connection has a minute to come back, with a robot keeping their seat warm. There are no decisions to make, so the robot levels are the same; the robots simply roll when it is their turn.

Common misunderstandings

1. "I passed a ladder, so I climb." Only a token that lands exactly on the foot climbs.
2. "A snake's tail is a ladder." No; landing on a tail does nothing.
3. "Three sixes is a penalty." Here a third six is simply the last of the run: you keep the squares you moved.
4. "I rolled a 6 on 96, I win." With the exact finish on, the roll is lost. Switch it off for a looser game.
5. "Two tokens can share a square." Landing on another player sends them home.

Glossary

• Exact finish: the rule that a token must land on 100 by an exact roll.
• Capture: landing on another token and sending it back to the start.
• Foot and head: the bottom of a ladder (where you climb) and the top of a snake (where you slide).
• Moksha Patam / Gyan Chaupar: Indian names for the ancestors of the game.