# Star Battle

## Rules

Place stars into some cells in the grid, no more than one star per cell. Each row, each column, and each outlined region must contain a given number of stars. Cells with stars may not touch each other, not even diagonally.

(Rules (modified) from PGP IB, example from WPC 2019 IB)

### Rule variations

• In Small Regions Star Battle, the number of stars per row and the number of stars per regions is different. The numbers are usually 2 for rows/columns and 1 for regions. See one example on GMPuzzle.

## History of the Puzzle

Invented by Hans Eendebak (Netherlands) in 2003. First appeared on WPC 2003/Part I.

This puzzle is based on an earlier puzzle called Cattle, [1] invented by Tim Peeters (Netherlands) in 1999. On this puzzle, there were four regions of five cattle each, and numbers of cattle place were given row by row, column by column.

## Variants

### Comet

Hybrid with Simple Loop. First appeared on the 8th 24-Hour Puzzle Championship (2007). The puzzle idea is by Serkan Yürekli (Turkey).

Place some stars of size one cell into the grid so that there is a given number of stars in every row, column and outlined region. Stars cannot touch each other, not even diagonally. Then draw a single closed loop passing through all the remaining white cells of the grid. The loop cannot touch or cross itself. There are no stars or loop segments in black cells.

(Rules from WPC 2016 IB, example (1 star) from the 8th 24hPC IB[2])

### Coloured Star Battle

First appeared on 2012 Indian Nationals.[3] Author of the puzzle was Deb Mohanty (India).

Place stars in some cells such that each row, column, and boldly outlined region contain the indicated number of different types of stars. Identical stars cannot touch each other, even diagonally. Different stars can touch each other, even orthogonally.

Any two different notations can be used to represent the two stars, as long as consistency is maintained through the grid. The usage of black and white stars to indicate the number of stars is arbitrary and can be completely switched within the solution.

(Rules and example (1 star each) from WPC 2017 IB)

### Myopia Star Battle

First appeared on WPC 2016/Round 10, a Myopia-related variant round. The author of the puzzle was Matúš Demiger (Slovakia).

Place stars into some cells in the grid, no more than one star per cell. Each row, each column, and each outlined region must contain a given number of stars. Cells with stars may not touch each other, not even diagonally.

The arrows point at all of the closest stars in the corresponding direction. No star can be placed in a cell already containing an arrow.

(Example (1 star each) from WPC 2016 IB)

### Starwacky

Hybrid with Heyawake with nonrectangular regions. First appeared on WPC 2018/Round 6. The puzzle was by Jan Zvěřina (Czech Rep).

Shade some cells in the grid. Each row, each column, and each outlined region must contain a given number of shaded cells. Shaded cells may not touch each other, not even diagonally. Additionally, any single horizontal or vertical line without a star cannot traverse more than one thick line.

(Example (1 star) from WPC 2018 IB)

### Star Battle (Builder)

Most likely originated from Murat Can Tonta (Turkey) in a 2021 post on GMPuzzles.[4]

Place stars into some cells in the grid, no more than one star per cell. Each row, each column, and each outlined region must contain a given number of stars. Cells with stars may not touch each other, not even diagonally. Some region boundaries are missing, but all given borders must separate cells in different regions.

(Rules and example from WPC 2023 IB)

### Star Battle (Double)

Most likely originated from Murat Can Tonta (Turkey) in a 2020 post on GMPuzzles.[5]

Place stars into some cells in the grid. Each row, each column, and each outlined region must contain a given number of stars. Cells with stars may not touch each other, not even diagonally.

There are some shaded cells in the grid. These cells contain either two stars or none. Unshaded cells contains either one star or none.