Mental Stretch 2D
Positions:
Colors:
Allow Duplicate Colors in a Row: yes no
Allow Duplicate Colors In a Column: yes no
How to play

Solution:

New Guess:
Colors:

History: (0 tries)

 
Instructions
Mental Stretch 2D is similar to the puzzle Mastermind, but extended to two dimensions. It is a code-breaker puzzle. The goal is to deduce the code in as few guesses as possible. The code is a grid of colors.

At the top of the game board you can select the number of positions, the number of colors, and whether to allow duplicate colors in the code on a row and/or column basis. These choices determine the puzzle difficulty. Note that if the number of colors is less than the number of positions then duplicate colors will be enforced.

The area below this is where you make your guesses. There will be a grid of squares (according to the number of positions chosen) with hashed backgrounds. To place a guess, you need to set a color in each of these squares and then click the "Try it" button. Colors are set by dragging colored boxes in the area titled "Colors:" to boxes in the "New Guess:" area.

Once you have placed your guess by clicking "Try it", your guess will display in the "History:" section (sorted newest to oldest). Per guess, for each row and for each column there is a number for "B" and for "W", where "B" is the number of black pegs and "W" is the number of white pegs (as seen in the classic Mastermind game). For a row, the number of black pegs tells you how many colors are in the correct location (it does not tell you which color or which location) in that row. Similarly, for a column, the number of black pegs tells you how many colors are in the correct location for that column. The number of white pegs tells how many colors are correct but in the wrong location. Use this information to guide in choosing guesses and in deducing the solution.

You can use peg information from rows and columns together to narrow down and deduce the correct colors.

You can lock/unlock colors by clicking on boxes in the 'New Guess' area. When locked, they have a thicker border and a greenish edge. Clicking on a box toggles this feature for that box. Locked colors will not change when you click the 'Random Fill' and 'Clear' buttons. Locking colors can also be useful in keeping track of which colors you think you have solved.

Per row (and per column), the total number of possible permutations (arrangements where order matters) of colors (allowing duplicates) is colors^positions where "^" means exponentiation. Thus, for the default setting of 5 colors and 3 positions there are 5^3 = 125 possible permutations. For the maximum challenge of 20 colors and 10 positions there are (allowing duplicates) 20^10 = 10.24 trillion possible arrangements! Note that the size of your device may limit the number of positions to fewer than 10.

Per row (and per column), if duplicates are not allowed, the total number of possible permutations of colors is colors!/(colors - positions)! (where "!" means factorial). Thus, for the default 5 colors and 3 positions there are 5!/2! = 5*4*3 = 60 possible arrangements. And for 20 colors and 10 positions there are 20*19*18*...*11 = more than 670 billion possibilities!

For more information on Mastermind clones, including strategies for solving, see Wikipedia


iOS Devices

You can add the Mental Stretch 2D web app to your iOS device:
1) Go to https://www.artbylogic.com/puzzles/mentalstretch2D/mentalstretch2D.htm in your Safari browser.
2) Tap the Share button (at the bottom of the Safari screen for the iPhone, at the top for iPad)
3) Tap the icon labeled "Add to Home Screen"
4) Tap the "Add" button in the upper right hand corner of the dialog
You can now launch the Mental Stretch 2D app from its icon on your iOS device.

Android

You can pin the Mental Stretch 2D web app to your Android device:
1) Go to https://www.artbylogic.com/puzzles/mentalstretch2D/mentalstretch2D.htm in your browser.
2) Click the Menu button. Then add the page to your bookmarks.
3) Open your bookmarks using the menu button. Find the new bookmark you just added. Press down and hold on the bookmark until you see an action menu.
4) Select "Add to homescreen" from the action menu.
The bookmark is now pinned to the homescreen for easy access.


Enjoy!
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