Star Battle

Overview

Star Battle places stars on a grid divided into irregular outlined regions. In this introductory board, each row, each column and each region must contain exactly one star. Stars cannot touch along an edge or at a corner. The row and column restrictions alone resemble a placement puzzle, but the irregular regions introduce another set of competing choices. A star that completes one region may eliminate the only remaining position in another. The no-touching rule is what gives the puzzle its texture: every confirmed star removes a three-by-three patch of the board from play, so each placement is also a small act of elimination. This locally hosted pzpr player provides a checked six-by-six introductory puzzle. Eight selectable practice orientations rotate or reflect that same arrangement; they are not advertised as separate original levels. You can mark excluded squares, undo decisions and request answer feedback while learning how the three counting systems interact.

How to Play

Click an empty cell to place a star. Secondary input marks a cell as unavailable; enable the Secondary toggle for those exclusions on a phone. Place one star in every outlined region while also using each row and column once. Leave a full one-cell neighbourhood around every star free of other stars, including diagonals. Use the exclusion marks aggressively: ruling a cell out is reversible and safe, while a wrongly placed star can mislead you for many moves. Press Check answer when you want to validate your arrangement. Restart clears the attempt, Undo reverses the latest change, and the orientation selector offers a transformed view of the same introductory puzzle.

Tips & Strategy

After placing a star, exclude the rest of its row, column and region as well as its eight immediate neighbours. Then look for a region with only one legal position remaining. A narrow region occupying a small number of rows can constrain other regions even before its star is fixed. Compare candidate positions across region boundaries rather than solving each outlined shape independently. Near the finish, count stars by all three systems: six stars in six rows do not automatically satisfy the regions. Practising a rotated board is useful for checking whether your reasoning depends on memorised locations rather than the placement rules. When you feel stuck, stop hunting for where a star can go and ask instead where a region's star cannot go; exclusion usually moves faster than placement.

Using Region Shapes

Region geometry produces some of the strongest deductions in Star Battle. A region that fits entirely inside one row forces that row's star to live inside the region, so every other cell of the row can be excluded at once. The same holds for a region contained in a single column. A second pattern: any two-by-two block of cells can hold at most one star, because every pair of cells inside it touches along an edge or a corner. A region shaped as a compact clump therefore spends its star budget quickly.

Here is a worked example. Imagine a region consisting of exactly two stacked cells in column three, rows four and five. The region's star is automatically column three's star, so exclude every other cell in that column. Whichever of the two cells wins, the star touches the cells beside it in columns two and four across both rows, so those four cells are excluded too. Two rows have now lost candidates in the neighbouring regions before a single star was placed there.

Common Pitfalls

• Forgetting the diagonal rule. Edge-adjacent stars are obviously illegal, but corner-touching ones slip through constantly; after each placement, check all eight neighbours.
• Losing count near the end. On a six-by-six board the sixth star is often forced into the only legal cell left, but only if your exclusion marks have been faithful.
• Verifying rows and columns while neglecting the regions. All three systems must read exactly one star each.
• Memorising a solution layout. The rotated practice boards punish pattern memory, which is precisely why they are useful training.