All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Games
5-by-5 Square Tic-Tac-Toe (Posted on 2012-01-26) Difficulty: 3 of 5
My brother and I used to play a game we created called 5-by-5 Square Tic-Tac-Toe. The game is played on a 5-by-5 grid. The players place their respective symbol (either X or O) in an available square. The object of the game, rather than to get three-in-a-row like in Classic Tic-Tac-Toe, is to create a square using 4 of one's own symbols.

Here's an example to help demonstrate some strategies:

+ - + - + - + - + - +
|   |   |   |   |   | 5
+ - + - + - + - + - +
|   |   | O | X |   | 4
+ - + - + - + - + - +
|   |   | X |   |   | 3
+ - + - + - + - + - +
|   | O |   | X |   | 2
+ - + - + - + - + - +
|   |   |   |   |   | 1
+ - + - + - + - + - +
  A   B   C   D   E

Here, after X's third move, O must play E3 to block the square X is threatening. X must then play D1 to block O's square.

+ - + - + - + - + - +
|   |   |   |   |   | 5
+ - + - + - + - + - +
|   |   | O | X |   | 4
+ - + - + - + - + - +
|   |   | X |   | O | 3
+ - + - + - + - + - +
|   | O |   | X |   | 2
+ - + - + - + - + - +
|   |   |   | X |   | 1
+ - + - + - + - + - +
  A   B   C   D   E

At this point, O can not threaten another square, so her best strategy is to block as best she can. Suppose she plays C2, which would mean she can block two of X's possible threats (D3 and C1), and has the additional advantage of offering three potential threats for her next move: B1 (threatens C1, and vice versa, noted below with G), A4 (threatens A2, noted with I ), and B4 (threatens D5, noted with H ).

+ - + - + - + - + - +
|   |   |   | H |   | 5
+ - + - + - + - + - +
| I | H | O | X |   | 4
+ - + - + - + - + - +
|   |   | X |   | O | 3
+ - + - + - + - + - +
| I | O | O | X |   | 2
+ - + - + - + - + - +
|   | G | G | X |   | 1
+ - + - + - + - + - +
  A   B   C   D   E

The game plays out with X playing E2, O blocking with E1, and X plays B3. O blocks with C1, X counter-blocks with B1, and O blocks with D3 (It might help you to draw this out on a piece of paper, one move at a time). Finally, X plays A4.

+ - + - + - + - + - +
|   |   |   |   |   | 5
+ - + - + - + - + - +
| X |   | O | X |   | 4
+ - + - + - + - + - +
|   | X | X | O | O | 3
+ - + - + - + - + - +
|   | O | O | X | X | 2
+ - + - + - + - + - +
|   | X | O | X | O | 1
+ - + - + - + - + - +
  A   B   C   D   E

O is unable to block both A1 and D5, so X wins on his next move.

+ - + - + - + - + - +
|   |   |   | X |   | 5
+ - + - + - + - + - +
| X |   | O | X |   | 4
+ - + - + - + - + - +
|   | X | X | O | O | 3
+ - + - + - + - + - +
|   | O | O | X | X | 2
+ - + - + - + - + - +
| O | X | O | X | O | 1
+ - + - + - + - + - +
  A   B   C   D   E

My brother refuses to play any more, because he believes whoever plays first always wins, assuming everyone plays with optimal strategy and makes no mistakes.

Is my brother right? Can the player who goes first always win?

No Solution Yet Submitted by Dustin    
Rating: 4.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
No Subject | Comment 2 of 7 |
I'm not good at tic tac toe but I appreciate your work. I believe it's hard to win for 2nd player. doge2048
  Posted by Michael on 2018-10-27 07:55:10
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (14)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information