ALL THE KING'S HORSES

Copyright (c) 1976 John Conway

This game is played on the following 8x8 square board:

 

BARN - The top left 2x2 cell area (marked in the diagram). HORSE - A horse moves one cell orthogonally and then one cell diagonally on the same direction (like the chess Knight). However, after the move, the horse must be closer to the barn. Several horses may occupy the same cell. SETUP - Define a number of horses. Then, at each turn, each player drops one of those horses on an empty cell. Let's assume a default value of 8 horses. MOVE - On each turn, each player moves all the horses. When a horse enters inside the barn it is removed. GOAL - Loses the player that remove the last horse.

 

An example With this position, the next player wins the game. He will remove three of the four horses (b5, b6 and d7) and move horse e6 to c7 (or d8). The next player must remove that horse (moving it to a8) and lose the game.

This is a NIM-like game. Possible variants are: (i) wins the player that removes the last horse, (ii) only move one horse at a time and horses may not share cells (iii) use just one horse which can make four types of move (up then right or left, and west then up or down) and a stack of N stones. At the player's turn, he either move the knight or remove at least one stone from the stack. A player wins if, after his turn, the horse is in the barn and the stack is empty.

Another game is Wyt Queens which is basically the same game played with queens. Players drop several queens (each cell may contain more than one piece) and then each player moves a queen per turn. Queens may move North, West and North West. When all queens are at the top-left cell, wins the last player that moved.