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Last Updated: May 7, 2019

Ladder

Introduction

If you're here wondering about a Korean social game for prizes, known as ladder of ghost leg, Sadaritagi in Korean, or Amidakuji in Japanese, I can't do any better than the Wikipedia page on .

This page explains a simplified version of Ladder by . In Gameplay's version, every game will randomly choose three elements and the player will bet on what they are.

Rules

  1. After the players bet, the game will have an animation of a path being traced down the legs and rungs of a ladder. The player may make the following bets on the details:
    • Left or Right — Whether the path will start on the left or right side at the top.
    • Three or Four — Whether there will be three or four rungs in the ladder.
    • Parity — The two legs of the ladder are labeled with an O for Odd and E for Even at the bottom, in random order. Which letter the path ends in determines whether Odd or Even wins. I should stress this is not correlated to the number of rungs nor the parity of the animation in any way that I can tell.
  2. Wins on a single element of the game (left, right, odd, even, three, or four) pay 1.95 for 1.
  3. The player may parlay the parity (odd or even) with the number of rungs (three or four). Wins pay 3.88 for 1.

Analysis

The single element bets have a 50% chance of winning and pay 1.95 if they do. This results in an expected return of 0.5 × 1.95 = 97.5%, or a house edge of 2.5%.

The parlay bets have a 25% chance of winning and pay 3.88 if they do. This results in an expected return of 0.25 × 3.88 = 97.0%, or a house edge of 3.0%.

  • — Play for free at the Gameplay Interactive web site

Written by: Michael Shackleford

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