Arithmetic grids & Nonograms

Fill runs with digits 1–9 that sum to the clue and do not repeat inside the run. Crossing runs share a cell that must sit in both sum partitions — that intersection is the usual opening.

Latin-square rows/columns plus cages that hit a target with +, −, ×, or ÷. Operator and target sit on the cage; the hard part is candidate sets that fit both the house and the cage.

Place the required stars per row, column and region so that no two stars touch — not even diagonally. Regions replace Sudoku boxes; the exclusion neighborhood is the real constraint.

Each cell is a building height 1…N. Outside clues count how many buildings are visible along that line; taller buildings hide shorter ones behind them.

Pair each tree with an orthogonally adjacent tent. Tents do not touch even diagonally. Row/column numbers fix how many tents sit on that line.

Partition the grid into regions, each with one center mark, each region 180° symmetric about that center.

Each region gets one L, I, T or S tetromino. All tetromino cells form one connected shaded set; no 2×2 shaded block; identical shapes usually cannot touch across borders.

Join equal number pairs with orthogonal paths that do not branch or cross. Many contest grids also require every empty cell to be used.

A Latin square of size N with < or > between some adjacent cells. Inequalities prune candidates before you finish the square.

Fill regions with 1…size. Equal digits in the same row or column must be separated by at least that many cells (two 4s need at least four cells between them).

Outside numbers are lengths of contiguous shaded blocks in order. Gaps of at least one unshaded cell separate blocks. No algebra — placement and counting.

When a block is long relative to the line, the leftmost and rightmost legal placements overlap in the middle; those overlapped cells must be shaded. Iterate across rows and columns.