Alcazar - A Sudoku without numbers

It's a new kind of logic puzzle with thrilling gameplay and deep logic. More intense and visual than Sudoku, it may be the best pencil puzzle of the decade.

Alcazar: playtest

Alcazar - Volume 1

Alcazar is a new kind of puzzle with thrilling gameplay and deep logic.

This series of 100 puzzles was carefully designed and tested to offer a unique and engaging challenge of increasing difficulty.

It's new, it's better than Sudoku, and it fits in your pocket!


Includes game rules and tips in English, French and German.

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Try some puzzles

The rules

Alcazar is a new kind of puzzle with thrilling gameplay and deep logic, which come from surprisingly simple rules:

1. Enter from one door, exit from another

2. Cross every space exactly once

3. Each puzzle has a unique solution

Instead of just guessing, use deduction to build the solution, segment by segment. This is how you sharpen your logic skills and improve your techniques for the next level.


Print and play!

Sample puzzles as pdf
Adobe Acrobat Document 6.1 MB





Another useful Alcazar technique: Bouncing

One Way, puzzle 1 - Click to play in your browser
One Way, puzzle 1 - Click to play in your browser

Let's have a look at the first puzzle of the book One Way, in the Alcazar app (available for iOS and Android).


With a bit of experience in puzzle solving, you will probably start this one by filling the squares that have two walls (corners and pipes), and end up with all the black lines on the image.


Experts will go one step further and trace all the red lines on this image. With some practice, this step will become trivial, and you will do it automatically.

But what is it about? It's a simple technique that I call Bouncing. I'll show you how to use it in the 4x2 upper-right room of this puzzle. 


The basic idea of bouncing is the same as the Weak Points technique that I presented a few months ago, when Alcazar was still a paper-only puzzle. Start by completing square #1 (it's a corner), and move to square #2. Notice that there are only two possible ways to cross that square: left-up (A), or left-right (B). In conclusion, you must enter this square from the left.


Now you can start bouncing. Very often, when you draw a conclusion from a weak point like this, you create another weak point in a nearby square. You can bounce from square to square and draw many conclusions for the price of one.


In our example, let's bounce to square #3. Because of the line that we traced in square #2, it's now impossible to cross square #3 down-right: this would automatically create a 6-squares cycle. Thus, there are only 2 possible ways to cross square #3: left-down (A) and left-right (B). In conclusion: you must enter this square from the left.


Let's continue bouncing! There are 2 ways to cross square #4: right-down (A) or up-down (B). Conclusion: you must enter from the bottom.


This technique can be used in the vast majority of Alcazar puzzles. If you play often, this will be automatic for you. You will bounce from square to square without thinking about it.


Have fun, go ahead and try it!








Solution to the impossible puzzles

A few weeks ago, I proposed two Alcazar puzzles that have no solution. Some readers came up with very clever ways to explain why they are impossible. Here is my summary.


The key idea is to notice that all the possible lines fall into two categories: those that fill an even number of squares, and those that fill an odd number of squares. When the puzzle is colored like a checkerboard (black, white, black, white...), you can extract important information about these lines (see image).

Solution to the first puzzle

With 18 white squares and 17 black ones, we need an odd path to fill this room, and it needs to start and end on a white square. Unfortunately, there is only one door on a white square. This is why the puzzle has no solution.

Solution to the second puzzle

It was meant to be much harder than the first one, but "jh" (one of the blog's reader) came up with a very elegant solution that I summarize here. Congratulations, jh!


Like the first puzzle, this one has an extra white square, which means that the solution must start and end on a white square. We can close all the black exits of the puzzle.


Then, let's have a look at the 6x6 area in the bottom right. It has as many white squares as black ones, which means that if we want to fill this area with a single line, this line will need to start on a white square and end on a black one (or vice versa). But now that the puzzle's black exits are closed, this area has only white exits. In conclusion: we cannot fill it with a single line.

One last question remains: could we fill this area with more than one than one line? In other words, could we enter this area, exit, and then enter it again? Let's see...

There are only 3 squares that link this area to the rest of the puzzle and they are white. It means that we must enter and exit on white squares with our first path, and then, enter again on a white square before exiting the whole puzzle (again, on a white square). Each of our lines will cross one extra white square, but the area doesn't have extra white squares.

And that's why the puzzle has no solution.

What about normal puzzles?

Click to play in your browser
Click to play in your browser

When playing some of the advanced puzzles in the real game, using the square colors can be very useful. Look at the first level of the book "The Six Rooms", for example. The upper right room has an even number of squares and 4 exits: 3 are white and one is black. Conclusion: you must use the black one.

I hope that this article was helpful. Don't forget to get the Alcazar app (iOS and Android), and if you like it, leave a comment and a rating!

> Click here for the iOS version

> Click here for the Android version

In other news, you can now get the new edition of my game Manifold from Brainwrights' website.

Have fun!







These puzzles have no solution

Small Alcazars can be solved with just a bit of intuition, but as you tackle larger levels, the many elegant and complex techniques of the game become more and more relevant.

It's much more fun to find these techniques by yourself than to read about them, so let me simply propose an exercise that may put you on the right path. Here are two Alcazar puzzles. I made the first one, and the second one was created by Edderiofer. Don't try to solve them! They are both impossible. But why? How can you prove that they have no solution?

Leave your questions and hints in the comments! You may use ROT13 ( to hide important clues for those who don't want to see them. I will give a complete explanation in about a week. Have fun!

By the way: the Incredible November sale ends very soon. Make sure to order your copies of the Alcazar book before it ends!






An excellent hand-made Alcazar

This puzzle was made by Reddit user edderiofer, who was also one of the most active beta-testers of the Alcazar Android app.


With only 4 exits and lots of walls, it doesn't look so hard at first glance. However, you will soon realize that it's one of the most surprising and difficult Alcazars to date.


How will you approach it? If you find a simple and elegant way to solve it, please share it in the comments below. However, when you give a clue, make sure to encode it using this tool:


Click here for a full screen version of the puzzle.


Have fun!



An easy way to talk about different techniques is to use chessboard notation: column are called A,B,C... (left to right) and rows are called 1,2,3... (bottom to top).



- C3D4 has a wall

- The room A1:D4 has 4 exits 






Alcazar on Android

Alcazar for Android will be released on the 9th of July!

Would you like to talk about it on your blog, magazine or other media? Don't hesitate to get in touch with me directly!






Alcazar on Android - Screenshots

With an extraordinary group of beta testers, we are currently fine tuning the game. It's very exciting!


Today, we selected 8 screenshots to represent the game on the Google Play store. What do you think? Don't hesitate to leave a comment!






From Alpha to Beta

Thanks to everyone who asked to join the group of testers! I apologize for making you wait, but I have good news: next weekend, the app will enter a short beta test phase, and I will accept everyone who asked, as testers.


It also means that the Android app will soon be available for everyone!


If you didn't do it already, you can join the beta test by asking to be part of this group on Google+:








A new puzzle for the new Alcazar players

Have fun!

I made this puzzle for those who discovered Alcazar in the last week, since I released the book. By the way, I'd like to hear how you heard about the game!


Don't hesitate to post a comment. The Alcazar community is still very small.






Alcazar - Advanced puzzles

Hi everyone.


A puzzle expert, on Reddit, solved all the Alcazar puzzles on the website with very clever techniques, and recommended that I give a preview of some advanced puzzles.


Good idea! Here are 2 pages from Alcazar - Volume I that I would normally recommend to experienced Alcazar solvers.


Warning: these puzzles are for experts only! If you feel ready to try them, feel free to print the following pdf page.

Alcazar - Levels 77 and 97
Adobe Acrobat Document 1.0 MB

If you need to guess and erase too much, it just means that you need some practice. For that, the Alcazar book is available, and contains 100 puzzles from the easiest to the most difficult!

Alcazar #77
Alcazar #97






Alcazar: The Official Poster

An Alcazar fan had the idea to print a giant Alcazar, solve it, and hang it on his office door.


It's such a great idea that I made 2 official printer-friendly posters. If you like Alcazar, here are the instructions: Download it - Print it - Solve it - Show it!


Alcazar Poster Small (A4/Letter)
Adobe Acrobat Document 519.6 KB
Alcazar Poster Large (A3/11x17)
Adobe Acrobat Document 571.6 KB

Have fun!

Alcazar Poster
Download it - Print it - Solve it - Show it


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