8×8 Star Battle puzzles
What an 8×8 board asks for
One star per row, column and region. An 8×8 grid is divided into 8 regions and takes 8 stars in total — one in every row, one in every column, one in every region, and no two of them touching, not even at a corner. 1,382 boards, with 5.9 named techniques needed on an average one.
How hard they get
The rating comes from the solver: it adds up every step a board needs, and harder kinds of step count for more. Nothing is filled in at the start of any board, so a hard one is hard because its reasoning is longer and trickier.
- 1,382 one-star: 281 easy, 689 medium, 327 hard, 85 expert
Different techniques per level
How many different techniques a board needs on average, at each level. The rating is not this count: it weighs every step, so a higher level can need the same number of different techniques, or even fewer.
- One star: easy 5.4, medium 6.1, hard 6.1, expert 5.9
Which techniques an 8×8 board needs
Measured across every board in the pack, not estimated. A technique counts once per board, however many times it fires.
One star:
- Only enough room left — 100% of boards. Whenever eliminations have narrowed a row, column, or region down to just enough cells.
- Stars cannot touch — 100% of boards. Immediately after placing any star.
- A full line is closed — 100% of boards. After placing the last star a row, column, or region was owed.
- Cells caught between candidates — 98% of boards. When a row, column, or region is down to two or three open cells sitting close together.
- Several regions filling the same rows — 80% of boards. When two or three regions are each squeezed into the same small band of rows or columns, and no single one of them is confined on its own.
- A region trapped in a row or column — 73% of boards. When every open cell of a region sits in the same row, or in the same column, or spans just two of them.
- A row trapped in a region — 43% of boards. When every open cell of a row or column belongs to one region, or to just two.
Every one is explained, with an example, on the techniques page. A board is published only once it is checked to have exactly one solution that these techniques can reach, so no size ever needs guessing.
How this compares with the other size
An 8×8 board needs 5.9 different techniques on average; a 10×10 one needs 7.2. So 10×10 is the longer think of the two, and this is the better place to start.
Other sizes
- 10×10 Star Battle puzzles
- Every size, with the difficulty up to you
- Today’s puzzle — one board, the same for everybody
- The rules, in full