How to play Lusona
Lusona puzzles are inspired by sona, the sand drawings of the Chokwe people. A line weaves diagonally between a grid of dots and bounces off the edge, but at the start it is broken into several separate loops. Tap the gaps between dots to place small mirrors that the line bounces off, until it becomes one unbroken line using exactly the number of mirrors asked for.
Step by step
Look at the drawing
The line already weaves diagonally between the dots and bounces off the edge. Each separate line has its own colour and its own dash pattern, and the counter says how many there are.
Read the goal
Below the title you see how many mirrors of your own you must use, for example "Your mirrors: 0 of 3". The puzzle is solved when the drawing is one single line and you have used exactly that many.
Tap a gap to place a mirror
Tap the space between two neighbouring dots. One tap places a horizontal mirror, a second tap turns it vertical, a third tap clears the gap. The line bounces off a mirror instead of crossing there.
Join lines where they cross
Where two different lines cross, any mirror joins them into one. Look for a spot where two colours meet.
Turn mirrors that split the line
If a new mirror splits a line in two, tap again to turn it the other way. In every gap, at most one of the three choices splits the line.
Finish with one unbroken line
When the counter shows one line and the right number of mirrors, the puzzle is solved and your finished drawing is traced out in the sand.
The full rules
What you see
The puzzle shows a rectangle of dots on a sand-coloured board, for example 5 dots across and 4 down. A line already runs through it. It travels diagonally, passing between neighbouring dots, and when it reaches the outside it curls around the outer dots and turns back in, like a ball bouncing off the side of a snooker table.
Often the line is not one line at all but several separate loops. Each loop is drawn in its own colour and with its own pattern (solid, long dashes, dots and so on), and a counter above the board says how many lines there are, such as “3 lines — join them into one”.
The aim
Make the drawing one single, unbroken line that weaves around every dot, the way a traditional sona is ideally drawn in one movement. To do it you place small mirrors in the gaps between dots. Each puzzle tells you exactly how many mirrors of your own to use. The puzzle is solved when:
- the counter shows one line, and
- you have used exactly the number of mirrors asked for.
Placing mirrors
A gap is the space halfway between two neighbouring dots, either side by side or one above the other. Tap a gap to change it:
- One tap: a horizontal mirror.
- Two taps: a vertical mirror.
- Three taps: the gap is empty again.
Without a mirror, the two strands of line passing through a gap simply cross. With a mirror, they bounce off it instead, so the line takes a new route.
Some puzzles start with fixed mirrors, drawn dark with a round dot at each end. They are part of the pattern and cannot be changed.
How mirrors change the line
- Where two different lines cross, any mirror joins them into one line. This is the main way to bring the loops together.
- Where one line crosses itself, one direction of mirror keeps it in one piece and the other splits it into two loops. If a mirror splits your line, tap again to turn it.
- When you already have one line but need more mirrors, add them in the direction that keeps the line whole.
Watch the counter and the colours after every tap: they tell you straight away what the mirror did.
Winning
When the line is one unbroken loop and you have used the right number of mirrors, the puzzle is solved, and your finished drawing is traced out in the sand. There is no score and no time limit, so take it at your own pace.
Puzzles to choose from
- Daily puzzle: a new puzzle each day at Easy, Medium or Hard. Solving it on consecutive days builds a streak.
- Fresh puzzle: a new puzzle whenever you want one.
- Patterns: a collection of hand-made symmetrical patterns, from a 3 by 2 grid up to 7 by 5.
Easy puzzles have small grids and usually need only joining mirrors. Medium and Hard puzzles have bigger grids, more lines, and one or two extra mirrors that must fit in without breaking the line.
Tips for beginners
- Find where two colours cross. A mirror there always joins those two lines.
- Count before you tap. If you need 3 mirrors and there are 4 lines, every mirror must join two lines.
- Turn, don’t remove. If a mirror splits the line, the other direction usually fixes it.
- Use Undo freely. Trying a gap and taking it back is part of the fun.
- Start with the patterns. “First join” and “Little mat” show the idea in a few taps.
Common questions
What is a lusona?
A lusona (plural sona) is a drawing traced in the sand around a grid of dots, traditionally by the Chokwe people of north-eastern Angola and neighbouring regions. Accounts describe storytellers drawing them while telling a story, a proverb or a riddle.
Is this a traditional game?
No. It is a puzzle inspired by sona. The diagonal, bouncing line follows the way many sona are drawn, and the mirrors come from a way mathematicians describe these drawings. The patterns in the game are our own designs.
Why does a square grid need more than one line?
Without mirrors, a grid that is 3 dots by 3, or 4 by 4, always breaks into several separate lines. In general, a plain grid makes as many lines as the largest number that divides both its width and its height, so 6 by 4 makes two lines and 5 by 3 makes one.
What does the Hint button do?
It points to one gap and explains why, for example that two lines cross there or that a mirror is splitting the line. Press Hint again and it makes that change for you.
Can a puzzle have more than one answer?
Often, yes. Any arrangement that makes one unbroken line with the right number of mirrors counts as solved.
Where it comes from
Sona are sand drawings traditionally made by the Chokwe people of north-eastern Angola and neighbouring parts of the Democratic Republic of the Congo and Zambia. According to accounts gathered mostly in the twentieth century, storytellers would mark a grid of dots in smoothed sand and draw a line around them while telling a tale, ideally in one smooth movement. The tradition is much less practised today, and written sources, many by outside observers, differ on details. Mathematicians, notably Paulus Gerdes, have studied the regular patterns of sona; describing them with small mirrors grew out of that work, and this puzzle builds on that idea.
