Harary's generalized tic-tac-toe or animal tic-tac-toe is a generalization of the game tic-tac-toe, defining the game as a race to complete a particular polyomino (Harary called them "animals") on a grid of squares. It was devised by Frank Harary in March 1977.[1]
Harary tic-tac-toe is similar to the m,n,k-games, of which tic-tac-toe and Gomoku are examples; but in tic-tac-toe the first player is trying to complete either an I-tromino (a horizontal or vertical line of three squares) or a diagonal line of three corner-connected squares, whereas in Harary's game there is only a single polyomino involved.