What Is Star Battle?
Star Battle is a grid-based logic puzzle where you must place exactly N stars in every row, every column, and every bold-outlined region — simultaneously. The catch: no two stars may occupy adjacent cells, not even diagonally. That single rule creates a cascade of elegant deductions.
Star Battle puzzles were first published in the 2003 World Puzzle Championship.
The puzzle is also known as "Star" or "Two Not Touch" in some publications. It has gained a devoted following among logic puzzle fans for its clean ruleset and satisfying solve experience.
How It Works
- The grid is divided into regions outlined with bold borders (shown in distinct colors).
- Place exactly N stars in every row, column, and region (N = 1 for easy/medium, N = 2 for hard).
- No two stars may share a side or a corner — they need a full cell of separation in all 8 directions.
- Click a cell to place a star. Click again to cycle to a dot marker, then clear.
- Right-click or long-press to place a dot (marking a cell as empty helps reasoning).
- Conflicts are highlighted in red so you can correct mistakes easily.
Frequently Asked Questions
What are the rules of Star Battle?
You must place exactly N stars in every row, every column, and every bold-outlined region. No two stars may touch each other — not even diagonally. In a 1-star puzzle, each row, column, and region gets exactly one star. In a 2-star puzzle, each gets exactly two.
Is guessing ever needed?
No. Every Star Battle puzzle on whatifs.fun has a unique solution reachable through pure logic. Common techniques include elimination (a row is full, so other regions can be narrowed) and 'star trapping' where a region only has one possible placement. No guessing or trial-and-error is required.
What does 2-star mean?
The '2-star' designation means you must place exactly 2 stars in every row, every column, and every region. This dramatically increases difficulty because the extra star per region creates more interactions and requires deeper chains of logic. 2-star puzzles are typically played on larger grids (10×10 or more).
Last Updated: April 2026