Boxes

A pencil and paper game for two players.

Starting with an empty grid of dots (of any size, but often 10x10), each player takes turns to add a single line between any two adjacent dots, along the grid lines (i.e. not diagonally). If on their turn a player is able to complete the fourth side of a 1 x 1 box, the player places their initial in the box and places another line, which itself may complete another box. The player's turn continues until they place a line which does not complete a box.

The game ends when no more lines can be placed. The winner of the game is the player with the most boxes.

In Mexico this is called Timbiriche.

In the game theory literature, this game is a variant of Nim.