I wasn't kidding when I posted that the Knight's Tour has been on my mind recently.

So much so, that I've re-written my Knight's Tour web app from the ground up, and I'm making it available as a free web app as of today!

The new Knight's Tour app is available here. It still features the same 3 challenges as the original version (Landing on all 64 squares, ending a knight's move from your starting point, and ending on a chosen goal square), and now it has even more features!

If you're not already familiar with the Knight's Tour, check out the introduction from my tutorial. This same tutorial is also accessible from the web app's Help menu.

Shortly after the iPhone was released, I developed a version specifically for it, which is still available here. The screen is one size only, and the interface is packed tightly.

That was one of the major reasons for updating my Knight's Tour web app. The new version scales to best fit the available screen space, so the higher the resolution of your computer/mobile device, the bigger the board. If you change your browser size or your device orientation at any time, the board will quickly re-size.

When you first open the app, you'll see the chessboard and you're presented with the Options menu, which can be brought up by either touching/clicking the Options button in the upper left corner (not shown in the picture below), or by touching/clicking the board when no game is being played.



The New Game menu at the top allows you to choose which of the three Knight's Tour variations you wish to play by simply touching/clicking that, and then touching/clicking the appropriate level. The Help button takes you to another menu, where you can learn more about each aspect of the program. The Settings button takes you to another menu which allows you to customize the look and function of the Knight's Tour app.

The Cancel button simply dismisses the menu, which can also be done by touching/clicking anywhere outside of the menu.

Along with the scalable board, the settings are probably the biggest new feature of the Knight's Tour app. Here's an End on Goal Square game being played with the app's default settings: The background is a grey linen-style pattern, and the visited squares are highlighted simply by squares in two different shades of red:



For comparison, below is the same level, but with several settings changed. The background has been changed to a wood pattern, the visited squares are now green, and the path of the knight is now numbered! (Can you see how to finish the game on the target square?)



The other settings include the speed at which the knight moves (From .2 second up to .7 seconds to move to the next square), the ability to turn the algebraic notation (the a8-h1 coordinates) on or off, whether the undo features are available, and even whether you or the app sets up the starting position on the board!

While my original version had Undo features, the new version improves the operation. If the Undo features are on, an undo button will appear in the upper right corner after you move to your second square. Clicking this button will take you back 1 move. You can also undo a move by clicking on the previous square.

You can also have the app ask you to OK each undo, which highlights any backtracking of multiple squares.

The Knight's Tour app will let you know when you're trapped when you land on a square from which you have no possible moves. If the Undo feature is off, this also ends the game immediately.

If the total of each row and column of the numbers formed by your path are all the same number (260), then your Knight's Tour path can be said to form a semi-magic square. If this does happen, the app will automatically notify you of this fact at the end of a complete game. I added this as a sort of bonus feature, so you can grab a screenshot if you ever achieve this.

This is a very rare occurrence, as out of the 10s of trillions of possible knight's tours, only 140 are semi-magic squares. In other words, you're millions of times more likely to get hit by lightning than to accidentally form a semi-magic knight's square by luck. Obviously, this feature will be used more by those who are intentionally trying to create such a square.

Play around with this, and let me know of any comments or criticisms in the comments. I hope you enjoy my Knight's Tour app!