Puzzle types – Sudoku+

Sudoku 9×9

The classic. Fill the board so that every row, every column and every 3×3 box contains the digits 1 to 9 exactly once.

Find a cell where only one digit fits.
Look at which digits already sit in its row, column and box.
If only one is left, enter it. Otherwise write the candidates as notes.

A puzzle at the start – dark digits are givens.

Difficulty levels

There are four levels: Very easy, Easy, Medium and Hard. The higher the level, the fewer digits are given and the cleverer your deductions must be. On “Hard” there are no hints.

Kids Sudoku 4×4

The same idea, smaller and more colourful: on the 4×4 board the digits 1 to 4 appear exactly once in every row, every column and each of the four coloured 2×2 areas.

Perfect for little ones. Create a kids profile (under “Your account”): it opens straight on the 4×4 board and has no duels or leaderboards.

Four colours, four areas – each colour needs 1, 2, 3 and 4.

Killer-Sudoku

A normal Sudoku: every row, column and 3×3 box holds 1–9 exactly once. On top there are dashed cages. The small number in a cage is the sum of its digits – and no digit repeats inside a cage.

There are few or no given numbers: the sums carry the information. Start with small cages – 17 in two cells can only be 8 + 9, 6 in three cells only 1 + 2 + 3.

Two cage examples with their sum in the top-left corner.

You meet Killer Sudoku as a special puzzle – for example behind a door in the Advent calendar.

Number Streets

Every white run between black cells is a “street”: it holds consecutive numbers with no gaps – the order doesn't matter (e.g. 6-4-5).
No number appears twice in a row or column.
A number on a black cell blocks that number for its whole row and column.

Two streets in one row: 4-5-6 and 1-2-3. The 7 on the black cell can't appear again in this row or column.

Start with the longest streets and with numbers on black cells – they rule out the most.

Futoshiki

Fill the grid so every number appears exactly once per row and column (1 to 4, 5, 6 or 7 – depending on the grid size).
The signs between cells must hold – the point always faces the smaller number.

Read the board on the right like this: the first sign says “1 < 3”, the second “3 > 2”. Vertically, ∨ or ∧ sits between two cells – the point again faces the smaller number.

Start with chains of signs – that's where you find the smallest and largest numbers fastest.

4×4 example with four givens and five signs.

Towers

Every row and every column holds the numbers 1 to 5 exactly once.
A number is the height of a tower – 5 is the tallest.
A number outside the grid tells you how many towers you can see from there: a tall tower hides everything behind it.
Clues sit on all four sides. Each direction is counted on its own.

From the left: the 2, then the 5. The 1, 4 and 3 hide behind the 5 – the clue is 2.

Trickier: you see the 3, then the 4 (taller than 3) and the 5 – three towers, not just the tallest.

Special puzzles

Special puzzles – such as the weekly puzzle or the Advent calendar doors – demand more focus: there is no instant check. You fill in all the cells; only when everything is full is it checked. If something is wrong it is marked red for 10 seconds and then cleared – you fill those cells again until it fits.

You can pause at any time – your progress is saved. Special puzzles need an internet connection so you can continue on any device.