Only 4 colours needed

You probably get the Nobel prize if you find a gentle proof that you need only 4 colours to colour the entire map of the world or a globe. Yes, it seems that only 4 colours are needed and no neighbouring countries will have the same colour.

Here 100 "globes" for you to colour varying from easy to hard. And you can play every level in 6 different ways.

- CLASSIC MODE: Just colour the ball
- SHARP MODE: The same as CLASSIC but now a bit harder to solve
- TOGETHER MODE: The app will help you to colour the ball
- TACTICS MODE: A bit tricky: you colour till the app takes over. Can you make the app colour the entire ball?
- RELAX MODE: Colour only 4 areas. But choose the right ones.
- GREEN MODE: The green colour is missing. Now what?

1852. Frederick Guthrie had a brother: Francis and Francis had a problem. He could colour any map with only 4 colours and no neighbour area on that map would have the same colour. But how to prove that? So Frederick, who studied at the University College in London, went to his professor in mathematics De Morgan and told him about his brother's theory. De Morgan didn't even know that 4 colours were enough and passed the question the same day to another mathematician in Dublin: Hamilton. Hamilton responded that he had no time for that sort of a question, so De Morgan started to ask everyone to solve this 4 colour theorem.

The theory is simple and explainable to anyone, but finding proof seemed far from easy: 27 years later, on July 17, 1879, Alfred Kempe announced in Nature that he had a proof of the "Four Colour Conjecture". All mathematicians happy at last: somebody finally had find a solution for such a simple problem. Kempe was elected a Fellow of the Royal Society and was even knighted a few years later.

Oops, in 1890 a fellow called Percy Heawood discovered there was a defect in Kempe's proof. Now all mathematicians around the world felt the shame that they were fouled for 11 years. And shame was not their only problem: they had to start all over again to find proper proof. Heawood himself studied for another 60 years trying to find a neat solution. But he didn't.

Eventually it took more than a century: In 1976 the complete solution to the Four Colour Theorem was found, but the proof was no conventional proof at all: it was the first major theorem to be proved using a computer. So a proof that could not be verified directly by other mathematicians.

So, if you have that proof that is made of traditional logical steps, you are more than welcome to tell us. You might even get knighted.

Make one line

In total over 50 nice Slitherlink Puzzles.

- Tap on a thin line to make it thick
- Tap again to make a bullet
- Surround every number with exact that amount of thick lines
- Use two fingers to zoom in
- Make one long line

Somewhere at the start..

Almost at the end..

The aim was a nice puzzle that is certainly not too easy. But from the start you get 5 hints for free. Use them with care and you will come very far and possilbly to the end.

Good luck!

Make 10 lines

Thanks to a clever random generator you get an unlimited amount of puzzle games. And depending on your mood you can choose from 6 different levels.

The aim was a puzzle game, without a competing element: So the puzzle in front of you is your puzzle and your puzzle only. You can also choose the level of difficulty you prefer:

- If you are in the mood for no thinking at all: choose RELAX or EASY.
- Do you want to set your mind to something else: choose MEDIUM or TRICKY
- Are you in for a challenge? Try HARD or even DIABOLIC

A pretty logic puzzle game.

Difficult concepts are just difficult. Simple concepts are difficult to find. But here is one. In fact it's so simple that I crossed all over
Tom Cutrofello's Puzzle blog and checked over 2000 puzzles to see if someone had made this game before. But no, so I'm happy to present Capice !

You swipe a tile and it wil change places with it's neighbour. Adjacent tiles of the same color disappear. Your goal is to clear the floor.

Maybe it's strange to say but this game teaches you to work organized: so don't go for the quick destruction of tiles leaving a playground full of loose ends and holes. Instead, make a little extra effort and keep the floor in a neat rectangular form and you will see you can solve this puzzle. Good luck!

Make one line

A simple puzzle game with only 32 puzzle pieces. But together they are good for 892.616.806.656.000.000.000.000 possible combinations. For you to find the 1 solution.

There are 100 levels from simple to extremely hard, but do not worry: if you think a game is too hard then you can always use one of the three hints available at any level.

The start of a puzzle:

The solution of a puzzle:

- Swipe to turn the ball.
- Tap on the ball to turn the puzzle piece.
- Tap and hold a while if you are sure the puzzle piece is in the right position. The blue line will turn green.
- Too difficult? Tap on the "3H" button and then on a puzzle piece. It will turn red and turn in the right position. You get 3 hints in every game.
- Use two fingers to zoom in or out.

I was surprized myself that I made Loop Loop first, which has 180 puzzle pieces followed by One Line Weekly which has even more than one thousand puzzle pieces. Apparantly I had to invent these "difficult" games before I could make this relatevily simple Lonely Line with only 32 puzzle pieces. But simple might not be the right word here. Because, with only 32 puzzle pieces, a Lonely Line puzzle can be even harder than a One Line Weekly. Good luck.

This is more than a maze. It's 150 mazes in 10 different play modes.

- Traditional
- Bald Ball
- Inside Out
- 60 Sec
- Trail

- Wall Fall
- Tall Wall
- Holes
- Twist
- Vanish

Just a nice maze, with surprising play modes. An ideal break without ads. An offline single-player game to give you that relaxing moment.

Connect all the white elements and make one long line.

Start Puzzle:

Solution:

- Tap on a white element to make it turn
- Swipe to turn the whole object
- Use two fingers to zoom in
- Every week you get a new puzzle (starting on Saturdays)

ReadAndroidCentral Game of the Week, by Marc Lagace.

or

Droid Gamers comment One Line Weekly is out now, by Sam Siommons.

or

Tom Cutrofello's blog Best iPhone and iPad puzzle apps

or

Connect the cubes of the same color.

Start Puzzle:

Solution:

- Swipe over the screen to turn the cubes.
- Swipe over a colored cube to color other cubes.
- Tap short on a colored cube to make it grey.
- Tap long on a colored cube and all cubes of that color will turn grey.

The inspiration of making Cube Loop came from the game Flow or Free Flow from Big Duck Games.
Flow is a 2 dimensional game (a flat chess board) in which you have to connect the dots of the same colour.
After I made CUBICKS I thought it was nice to make a 3D Flow version. It was until later that I discovered that Big Duck Games is not the inventor of the game Flow.
The idea of Flow is from a great puzzler called Tom Cutrofello. He reviews puzzle games since 2009 and he also invented a puzzle game himself. The game is called Lab Mice Puzzle and that is the original Flow game that inspired me.
This is his blog Tom Cutrofello Puzzle Blog

An endless puzzle game with a beautiful result.

The surface of the blue ball is full of loose pieces. Connect all of these loose ends and free the ball so it can disappear. Like this:

In this game you experience the entire history of a planet called Cube and its moon Menu.

- Swipe over the screen to turn the cubes.
- Swipe over a colored cube to color other cubes.
- Tap short on a colored cube to make it grey.
- Tap long on a colored cube and all cubes of that color will turn grey.

This is about the history of planet Cube. From the very first moment of existance, the big bang, to these modern times in which we shoot astronauts into space to discover our universe. And from the ice age, millions of years ago, to the white city smog of recent days.

During your trip you will see that planet Cube gets in into trouble sometimes. But thanks to you, it can survive! So you can bring the planet to the moment best known as today. And when you arrive there, you can make the choice for tomorrow.

Tap to turn and forget everything else.

The surface of the cube is full of loose pieces like lines and angles and crosses. Connect all of these loose ends and free the cube so it can disappear.

Rotate the cube and change the colors of the grey cubes by tapping on them. In the end every row and column of each side of the cube should have four different colors.

Start Puzzle:

Solution:

The name CUBICKS is a mix of the words CUBES and LOGICS. Pretty obvious, but what about the letter K ?

The K shows that CUBICKS is also a mix of two games: RUBIK'S CUBE and SUDOKU. They both have a K pretty much at the end of the word. The K in Cubicks is a tribute to these other games.

In fact there is a small story that connects all three games. Cubicks is invented by Marcelo Pars. Years ago he went on holiday to the lakeside of Lago Maggiore in Italy with his wife and kids. Every morning he stepped out his tent, made a cup of coffee and set himself behind a sudoku. But on one morning the whole family woke up early to make a visit to the city Milano. It was a Sunday and a lot of shops were closed. But at a street corner there was a big black fellow who had installed himself behind a shelf where he showed all his second hand stuff. In the middle of that shelf there was this Rubik's Cube. Marcelo saw the cube and hesitated. He knew that buying this cube would be the end of happy mornings solving suduko's. The guy saw Marcelo looking at the cube. "It turns really easy," he said. "Why don't you give it a try?" From then on holiday looked more like work, the way Marcelo was struggling with that cube. But now he likes to think a seed was planted in his head that summer. A seed that grew in his mind to this game: Cubicks.

Make one line

Every week (starting Saturday) another truly sperctacular slitherlink puzzle.

- Tap on a thin line to make it thick
- Tap again to make a bullet
- Surround every number with exact that amount of thick lines
- Use two fingers to zoom in
- Make one long line

Somewhere at the start..

Almost at the end..

The aim was a challenging puzzle like a difficult sudoku in the weekend newspaper.

- So here no slow ramp to difficulty, starting with small puzzles
- No, here you only find huge puzzles without mercy.
- Good luck!