Drawing Puzzles

A drawing puzzle is a puzzle where you have to follow a set of rules to complete a drawing. Drawing puzzles are popular children's activities, such as Connect-The-Dots or Color-By-Number. More complicated puzzles, such as Nonograms, also exist and are popular among children and adults alike.

At Utrecht University, we do research into different possible types of drawing puzzles. We focus on variants of Connect-The-Dots: puzzles where you are given a piece of paper with a bunch of dots on it.


In a classical Connect-The-Dots puzzle, dots are numbered. The goal is to draw lines between dots with consecutive numbers. If a number is followed by a + symbol, you should skip to the next dot without drawing a line.


In a Connect-That-Dot puzzle, dots are not numbered, but each dot can have one or more small link. The goal is to draw a line from each link to the first other dot in that direction.

Try some generated Connect-That-Dot puzzles.


In Connect-The-Closest-Dot puzzles, dots are coloured. The goal is to draw a line from every dot to the closest other dot of the same colour. A dot can have multiple colours; in this case it should be connected to the closest dot for each of its colours.

Try some generated Connect-The-Closest-Dot puzzles.


In a Connect-The-Unit-Dots puzzle, there are only dots. The goal is to connect two dots with a line if they are at exactly the right distance from each other.

Try some generated Connect-The-Unit-Dots puzzles.



If you want to know more about the research behind this project, you can check the following publications.


The following people have contributed to this project.
  • Marc van Kreveld
  • Maarten Löffler
  • Frank Staals
  • Mira Kaiser
  • Tim van Kapel
  • Gerwin Klappe