Tents (tents and trees) — tents puzzle

Tents is a shading puzzle. Trees are given. You place a tent beside every tree so the tents stay apart and the numbers outside the grid all match. You can play grids from 6×6 up to 10×10, and every puzzle here has exactly one solution that you can reach by logic, with no guessing.

Rules

The board is an n×n grid. Some cells hold a tree. Every other cell is either a tent or grass. A number sits left of each row and above each column. That number is how many tents the line holds. Zero is printed, so a blank line is never a missing clue.

Each tree pairs with exactly one tent. The tent has to share an edge with its tree, across or down. Touching at a corner does not pair them. No two tents touch, even at a corner. When the pairing is done and every count matches, the puzzle is solved. Grass is the mark for a cell you have decided stays empty. It is part of the answer, not a pencil note.

Controls

Click or tap an open cell to cycle empty, then tent, then grass, then empty again. Shift-click, right-click, or a long-press cycles the other way. Drag across open cells to paint grass. Trees do not take a mark. Selecting a tree only moves the cursor.

On a keyboard, the arrow keys move around the grid. T or 1 places a tent. G, X, M, period, or 2 marks grass. Backspace, Delete, or 0 clears the cell. Space or Enter cycles forward. Shift with Space or Enter cycles backward.

A count turns teal when the tents on that line match it. It turns coral when the line has too many tents, or is finished and still short. Tents that touch, a tent with no tree beside it, and a tree with nowhere left for its tent turn coral while error highlighting is on. Press Hint for one mark the rules already force, with a sentence saying why. Undo and Redo step through your moves, and Reset clears every tent and every grass mark. When the grid is right, the board turns teal. The timer, Check, Print, and Download PDF sit with the other controls.

Techniques

Easy grids follow from the trees and the counts:

• No neighbour: a cell that does not touch a tree is grass.
• Zero line: a count of 0 makes every open cell on that line grass.
• Saturated line: once a line has its tents, the open cells are grass.
• Touch grass: a cell beside a tent is grass, because tents cannot touch.
• Lone tree: a tree with only one open side left takes a tent there.
• Fill line: a line that still needs a tent in every open cell, and those cells do not touch, fills them all.

Medium grids also need a look at how a line can finish:

• Diagonal pair: a tree whose two remaining sides meet at a corner makes that corner grass.
• Line case: every way to finish a line puts the same mark on one cell.

Hard grids add one wider step, still without guessing:

• Cross line: every way to finish a line covers a neighbouring cell, so that cell is grass.
• Pigeon: a few trees have only the same few cells left, and those cells do not touch, so each one is a tent.
• One try: assume a tent or grass, and keep the mark whose opposite cannot be finished.

Beginner tips

Start with the 0s. They clear a whole row or column at once, and the trees beside that line lose a side.

Then look for a tree with only one open edge. That cell is a tent. After you place it, mark every cell around it as grass, including the corners.

If you are new to Tents, start with the daily 8×8 easy grid. Move up once zeros, lone trees, and full lines feel natural.