Justin and Kurt were marooned on a tropical island with plenty of food and water. With nothing to do, the weeks in paradise became boring. One day a box containing a flat folding backgammon board washed ashore. The box contained one black and one white die, a doubling cube, and a complete set of 15 checkers for each side. The board was stained, but in overall good condition. However, neither man knew how to play backgammon and the salt water had damaged the instruction sheet.
They studied the faded instructions and correctly deciphered all the rules, except one.
Look at the checker plays and the comments made in the three money game positions below. What change in the rules of backgammon had the two castaways made?
1. Kurt rolled 2 and Justin rolled 1. Kurt played 13/10 saying “It’s impossible for you to hit my blot.” Justin then rolled and had a 4-2 to play. He made his 4-point.
2. Kurt played 5-4 bar/20, 6/2 and said “If I play 20/16, I will certainly be hit. 6/2 is safer.” Justin then rolled and played 4-4 by hitting and building his 5-point 12/20*(2).
3. Kurt played 6-1 and took off two men saying, “That was one of my worst rolls!” Justin redoubled to 16 and Kurt correctly passed.
Give up? "The Changed Rule" solution is HERE.