Noughts and Crosses
Players: Two - Also known as: Tic-tac-toe
Players take turns in marking squares on a 3 x 3 grid. The first player to get three squares in a row wins.
This is probably the best known pencil and paper game.
The game is played on a 3 x 3 grid, typically created by drawing two horizontal lines and two vertical lines on a piece of paper. One player is 'O' and the other is 'X'.
Players take turns in drawing their symbol in one of the cells. The first player to make a line of three of their symbol horizontally, vertically, or diagonally wins.
If both players play perfectly the outcome is always a draw, but with inexperienced players the game is just complex enough to make the game interesting.
For example, the following game shows how the first player can force a win by starting in the centre square if the second player is foolish enough to reply on the edge: