What is Snake?
Snake is a logic puzzle in which you trace a single winding snake through a square grid. The snake is one cell wide and forms an unbroken chain of cells from a fixed head to a fixed tail - the two ends are marked for you. Every cell either belongs to the snake or stays empty, and the body never branches: each cell along the snake connects to exactly two neighbours, while the head and the tail connect to just one.
The clue that turns this into a puzzle is the set of numbers around the edge. A number above each column tells you exactly how many cells in that column are part of the snake, and a number beside each row tells you how many in that row. On top of that, the snake obeys one elegant restriction: it never touches itself, not even diagonally, except along the turns it actually makes. Put the counts together with the no-touching rule and the whole snake is forced - there is only one way to wind it from the head to the tail.
- The snake is one cell wide, from a fixed head to a fixed tail.
- Every snake cell connects to two neighbours; the head and tail to one.
- Numbers above the columns count snake cells per column.
- Numbers beside the rows count snake cells per row.
- The snake never touches itself, not even diagonally.
- Every puzzle has exactly one solution, by logic alone.
How to play Snake online
Click or tap a cell to add it to the snake; click again to clear it. The head and the tail are fixed and always part of the snake. As you shade cells the body draws itself as a connected tube, and the numbers around the edge turn green the moment a row or column reaches its count and red if you shade one cell too many. Right-click a cell to mark a small cross when you are sure it stays empty - it never changes the puzzle, it just records your reasoning.
Check looks over your grid and flags any cell that disagrees with the unique solution, without telling you which way to fix it. Hint shades one correct cell - or clears a wrong one - Undo steps back through your moves, Reset clears everything you have shaded, and Solution draws the whole snake when you would rather study it than finish it. New puzzle builds a fresh board for the size and difficulty you have chosen.
- Tap a cell to add it to the snake; tap again to clear it.
- The head and tail are fixed and always part of the snake.
- Right-click a cell to mark it empty; it is just a note for you.
- Row and column numbers turn green when met, red when overshot.
- Check, Hint, Undo, Reset and Solution help when you get stuck.
The counts around the edge
The numbers do most of the heavy lifting, and the extremes are the place to start. A 0 means a row or column holds no snake at all, so you can cross it off entirely - and those empty lines often pen the snake into a narrow channel elsewhere. A count equal to the width of the grid means every cell in that line belongs to the snake, so shade the whole line straight in. Between the extremes, each number is a strict budget: once a line has its quota of snake cells, every other cell in it is empty, and once a line is one cell short with a single candidate left, that cell must be snake.
The real power comes from reading rows and columns together. A cell is only snake if both its row and its column can still afford it, so a column hungry for cells that crosses a row already full pins that cell as empty, while the reverse forces it to be snake. Sweeping back and forth between the row counts and the column counts, tightening each against the other, is how a grid that looks blank turns into one where whole stretches of the snake are suddenly certain.
- A 0 means the whole row or column is empty - cross it off at once.
- A count equal to the grid width fills that line completely.
- When a line reaches its number, every other cell in it is empty.
- A line one short with one candidate forces that cell to be snake.
- Read rows against columns: each count limits the other.
Grow the snake from the ends
Because the head and the tail are fixed, you always have two loose ends to build from, and a snake can only grow one way - each new cell must connect to the one before it. Trace the body inward from the head and the tail and very often the next cell has only one legal home: the no-touching rule blocks every direction but one, or a row or column count forbids all the others. Growing the snake from both ends until they meet in the middle is the most natural way to solve.
The head and tail are especially talkative when they sit in a corner or against an edge, where the snake has fewer directions to escape. A cell whose row or column is nearly full often has only one neighbour it can possibly join, which fixes the snake's next step. And whenever a move would force the snake to touch a cell it already occupies, or to leave a stub with nowhere to go, that move is illegal - which usually leaves exactly one cell that fits.
- Build inward from the fixed head and tail.
- Each new cell must connect to the snake already drawn.
- A corner head or tail has fewer escape directions, so it forces moves.
- A nearly full row or column leaves a cell only one way to connect.
- Grow both ends until the two halves of the snake meet.
The snake never touches itself
The defining rule of Snake is that the body never touches itself - not orthogonally and not even diagonally - apart from the turns the snake makes as it winds along. In practice this means two parts of the snake can never run side by side, and they can never sit corner to corner across a gap. The snake is forced to keep its distance from itself, leaving a clear margin of empty cells around every stretch of body.
That single rule is a constant source of deductions. It forbids the snake from filling any 2x2 block, it stops two parallel runs from hugging each other, and it rules out the diagonal near-misses where two segments would touch at a corner. Whenever a count or a forced end offers you two possible cells, the no-touching rule almost always eliminates one of them, because shading it would bring the snake up against a part of itself. Keeping that empty margin in mind is as much a solving tool as the numbers are.
- The snake never touches itself orthogonally, except along its body.
- It never touches itself diagonally either, apart from its own turns.
- So the snake can never fill a 2x2 block.
- Two parts of the snake can't run side by side or corner to corner.
- Use the empty margin around the body to rule moves out.
Where Snake comes from
Snake is a puzzle of the competitive and online puzzle scene rather than the classic Japanese magazines. It is a regular in puzzle championships and on the big puzzle collections - sites like janko.at, where it runs under its German name Schlange, and Cross+A among them - and its clean idea, a single non-self-touching path steered by edge counts, has made it a favourite to set and to solve. The picture of a snake threading head to tail through a grid is instantly readable, which has helped it travel widely.
Underneath the snake theme sits a tidy blend of two old devices. Counting clues along the margins are shared with Nonograms and Magnets, and a single non-branching path is the heart of loop and path puzzles like Slitherlink and Masyu. Snake fuses them: you count your way across the rows and columns while keeping one connected, self-avoiding line alive. That combination of counting and path-finding, with the extra spice of the no-touching rule, is what gives Snake its particular character.
Snake vs Nurikabe, Slitherlink and path puzzles
Snake belongs to the family of path puzzles, but it draws an open line rather than a loop. In Slitherlink you read numbered cells and join dots into exactly one closed loop; in Masyu you thread a single loop past black and white pearls. Snake instead asks for one open path with two fixed ends, the head and the tail, and it is guided by counting clues around the margins rather than numbers inside the grid. The instinct of following forced connections from a fixed point, though, is exactly the same.
The no-touching rule and the empty margin around the body give Snake a strong kinship with shading puzzles like Nurikabe, where you also keep a connected shape clear of solid 2x2 blocks. Where Nurikabe spreads islands of shaded cells, Snake stretches a single thin line, so it feels like Nurikabe's quieter, more linear cousin. If you enjoy the forced-move chains of Slitherlink or the connectivity logic of Nurikabe, Snake is an easy and rewarding next step that mixes a little of each.
- Slitherlink: clues count edges; you build exactly one closed loop.
- Masyu: thread a single loop obeying black and white pearls.
- Nurikabe: keep connected shaded shapes clear of 2x2 blocks.
- Snake: edge counts plus a single open, self-avoiding path.
- It bridges counting puzzles and path-drawing puzzles.
Grid sizes and difficulty levels
The 6x6 boards are the place to learn the moves: a short snake, counts that are easy to picture, and forced cells that follow quickly from the head and tail. On 7x7 the snake gets longer and winds further, so the no-touching rule and reading rows against columns start doing real work. The 8x8 boards are full puzzles - a long, twisting snake, counts that interact right across the grid, and stretches where you must follow the body and the numbers together before a single cell is sure.
Difficulty changes how many of the edge counts are revealed to start. Easy boards show every number, so each cell follows from a short, local deduction and the snake grows steadily. Medium hides some of the counts, leaving more of the snake to be reasoned out from the no-touching rule. Hard reveals the fewest numbers, so you lean hard on the no-touching margin and the remaining counts for longer before the snake takes shape. Whichever you choose, every board is checked by a solver before you see it and only those with exactly one solution are kept - so each puzzle is always solvable by pure logic, never by guessing.
- 6x6 - a short snake and gentle counts to learn the rules.
- 7x7 - a longer snake and more interplay between the counts.
- 8x8 - a twisting snake and deductions that cross the whole grid.
- Easy, medium and hard change how many counts are revealed.
- Every puzzle is verified to have exactly one solution.