How to play

Tents and Trees is played on a square grid with some trees already in place. Numbers sit beside each row and above each column.

1. Place tents in empty cells so that every tree has exactly one tent of its own, directly above, below, left or right of it. Diagonal cells do not count.
2. Every tent belongs to exactly one tree. The number of tents equals the number of trees.
3. Tents never touch each other, not even diagonally. Trees may touch.
4. The number beside a row or above a column says exactly how many tents are in that line.

The puzzle is solved when every tree is paired and all the counts match.

Strategy

Zeros first. A row or column with a 0 has no tents. Mark it all as grass.

Cells far from trees. A cell that is not orthogonally next to any tree can never hold a tent. Mark these as grass early and the grid shrinks quickly.

Full lines. When a row's count equals the number of cells still open in it, all of them are tents. When the count is already met, every other cell in the line is grass.

Ring of grass. Every tent forces the eight cells around it to be grass. Fill that ring the moment you place a tent.

Lonely trees. If a tree has only one free neighbour left, its tent must go there. This often happens near the edge or when trees are packed together.

Pairing. Tents must match trees one to one. If two trees can only use the same single cell, you have gone wrong somewhere. If a tent is the only possible partner for a tree, that tent cannot also serve a different tree, so the other tree must look elsewhere.

Counting in blocks. Two tents in the same row can never be in neighbouring cells. So if a row's only open cells form a run of three and the row needs 2 tents, they go on both ends of the run. Short runs with high counts are easy wins.

Rows and columns together. A row count often limits a column. If a row needs one more tent and only one of its open cells also has room in its column count, the tent goes there. Cross-check both numbers for every open cell late in the puzzle.

History

Tents and Trees is a pencil puzzle in the same family as the Japanese logic puzzles of Nikoli. It is widely known as Tents from Simon Tatham's Portable Puzzle Collection and appears in many puzzle books and apps under the name Tents and Trees.

Playing on Summoned Games

Pick 6×6 (easy), 8×8, 10×10, 12×12 or 15×15 (hard). New puzzles are generated as you go, so you can play as many as you like, and each one is checked by a solver to have exactly one solution. The daily puzzle is an 8×8 that is the same for every player that day. Solve it on consecutive days to grow a streak.

On a phone, tap a cell to cycle grass, tent and empty. The Tent/Grass button switches tapping to mark grass directly. Tap a row or column number once its tents are all placed to fill the rest of that line with grass. On a desktop, right click marks grass, the arrow keys move the cursor, Space or Enter cycles, T places a tent, X or period marks grass, Backspace clears, G switches mode, H gives a hint, C checks, U or Ctrl+Z undoes and Escape opens the menu. Zoom appears on 12×12 and 15×15 grids.

Counts change colour when a line is met or over. Touching tents are highlighted. Hint places one correct tent, or removes a wrong one. Check marks wrong tents and counts each one as a mistake. The win card shows your time, mistakes and hints. Progress saves automatically, solved puzzles go on the puzzles solved leaderboard and random 10×10 times on the fastest 10×10 board. A How to play guide is on the menu.

FAQ

Can tents touch diagonally? No. Tents may not touch in any direction, including diagonally. Trees can touch each other freely.

Does a tent next to two trees count for both? No. Each tent belongs to one tree only, so you need as many tents as trees.

Is every puzzle solvable with one answer? Yes. Every generated grid is run through a solver and kept only when it has exactly one solution.

What does marking grass do? Grass is a note for cells you know are empty. It does not change the solution, but it keeps the open cells easy to see.

Are hints and checks penalised? Hints are counted and shown on the win card, and each wrong tent found by Check adds a mistake. Neither adds time, and a puzzle solved with hints still counts as solved.