Tents and Trees puzzle

Tents and Trees is a deduction puzzle built from three rules that interact more deeply than they first appear. Every tree needs exactly one tent in an orthogonally adjacent square. No two tents may touch one another, even diagonally. Numbers around the grid state the exact number of tents in each row and column. The challenge is to make all three conditions true at the same time without guessing.

How the one-to-one pairing works

A tent only belongs to a tree when the two cells share an edge. Diagonal contact does not create a pair. It is also not enough to place the correct total number of tents near some trees: the final layout must support a one-to-one matching where each tree receives one tent and each tent belongs to one tree. This matters when two trees compete for the same open square. A placement can satisfy a row count and still fail the pairing rule.

The V0.122 source bank is generated locally rather than downloaded from a puzzle service. A candidate board begins with a legal non-touching tent layout. Trees are then placed beside those tents, row and column counts are derived, and a separate backtracking solver receives only the public puzzle information. The board is accepted only when that solver counts exactly one legal tent placement.

Use row and column counts early

A clue of zero is immediate information: every non-tree cell in that line is grass. If a row needs two tents and you have already confirmed both, all other undecided cells in that row are grass as well. The same is true for columns. Conversely, if a row still needs two tents and exactly two possible cells remain, both become forced. Strong solves move repeatedly between row counts, column counts and tree adjacency rather than working on one rule in isolation.

The no-touch rule creates exclusion zones

Once a tent is known, all eight surrounding cells are impossible for other tents. Marking those cells as grass can collapse several neighboring trees to a single candidate. This is why one forced tent often starts a chain of deductions across the board. The rule includes diagonals, so a tent in one row may eliminate candidate squares in the rows immediately above and below.

Tree candidates are often more useful than empty cells

For each tree, inspect its orthogonal neighbors that are not trees and have not already been ruled out. A tree with only one available neighbor forces a tent there. Two nearby trees may share candidate cells, which is where one-to-one reasoning becomes important. If one tree can use only a shared square but the other still has an alternative, that relationship can settle both trees.

Grass is a reasoning mark, not a guess

Grass simply means “a tent cannot go here.” It does not need to be completely filled for the puzzle to count as solved; only the final tent placement matters. The browser game lets a cell cycle between blank, tent and grass. Right-click can toggle grass directly on desktop, while keyboard and touch controls keep the same three-state model available without a mouse.

What Check, Hint and Auto Grass do

Check highlights conflicting tent placements, such as a tent that is not part of the verified solution, a touching pair, or an exceeded row or column. Because that feedback reveals correctness, the run becomes Assisted. Verified Hint applies one cell from the independently verified source solution and also marks the run Assisted. Auto Grass is narrower: it fills cells that are already impossible from visible rules, including cells that cannot touch any tree, cells around placed tents, and remaining cells in a completed row or column.

Three board sizes, one rule set

Easy uses a 6×6 board with six trees and tents. Standard expands to 8×8 with ten. Challenge uses 10×10 with fourteen. Larger boards do not add arbitrary rules; they increase the number of overlapping candidate relationships and row-column interactions you must track. The same core deductions remain valid at every size.

Why unique solutions matter

A puzzle that allows two different legal tent layouts is not a fair deduction target because the clues cannot distinguish which answer was intended. V0.122 therefore treats uniqueness as a release property, not a marketing label. The project verifier independently checks all 60 frozen source boards, confirms all eight symmetry transforms are structurally valid, and replays thousands of deterministic Practice selections before the release can be sealed.

Practice without changing Today’s 6

Tents & Trees is a specialist Practice game. Choosing a board, using a hint, completing a puzzle or building its specialist Daily streak does not add a seventh game to Today’s 6 and does not change the frozen Daily Score rotation. Practice seeds are stabilized in the URL so the same link reproduces the same source board and symmetry transform on the same release.

A practical solving order

Start with zero clues and cells that are not adjacent to any tree. Then scan for trees with one candidate. After placing a forced tent, mark its eight-cell exclusion zone. Recheck row and column clues, especially lines that have just reached their required count. Repeat that loop before considering more subtle shared-candidate relationships. Most progress comes from repeatedly propagating simple facts rather than making speculative placements.