Star Grid
One in every row, column and colour, and none may touch
How to play
Star Grid is a free online logic puzzle, known to puzzle fans as one-star Star Battle or the queens puzzle: place one star in every row, column and colour so that no two touch. A board takes a few minutes. It plays in any browser on phone or desktop and inside Telegram via @MatsuriGamesBot, with no download, in a plain look or a cosy one where the stars are cherries on tablecloths. Solve the daily board or pick a size from 5×5 to 9×9.
Star Grid is a short logic puzzle, known to puzzle fans as one-star Star Battle or the queens puzzle. The board is split into coloured regions, as many as it has rows. Place exactly one star in every row, every column and every colour, so that no two stars touch, not even at a corner. Tap a square once to place a star, twice to cross it out, and a third time to clear it, or drag to cross out several at once. Once a star is down, small dots show the squares it rules out. Two stars that clash are joined by a line straight away, and nothing is lost: undo, clear the board or ask for a hint, which explains its step and costs a tenth of the score. Boards run from a one-minute 5×5 to a thoughtful 9×9, and each has exactly one solution that logic alone can find, no guessing. The daily board is a 7×7, the same for everyone, and a level ladder grows with you.
- Place one star in every row, every column and every colour. Two stars can't touch, not even at a corner.
- Click a square once to place a star, twice to cross it out, a third time to clear it; drag to cross out several. Right-click crosses too. Keys: arrows move, Space cycles, X crosses, C places a star.
- Dots show what a star rules out, and a clash is marked at once and costs nothing. Undo (U) and the broom are free; a hint (H, twice) explains its step for a tenth of the score.
How to play Star Grid
The board is a square split into coloured regions, as many as it has rows. Place exactly one star in every row, every column and every colour. Two stars may never touch, not along a side and not at a corner.
Tap a square once to place a star, twice to cross it out and a third time to clear it, or drag to cross out several at once. Crosses are your own notes and never cost anything. Once a star is down, small dots mark the squares it rules out.
If two stars break a rule they are joined by a line at once, and it costs nothing. Undo goes back as far as you like, and the broom clears the board. A hint takes off whatever cannot stay, or shows the next step with its reason, for a tenth of the score.
A clean solve scores 400 on a 5×5, 600 on a 6×6, 800 on a 7×7, 1000 on an 8×8 and 1200 on a 9×9. A solve always keeps at least three tenths of that, however many hints it took. Time does not count, so a perfect solve ties with every other perfect solve.
Star Grid strategy and tips
- Begin with the smallest region. A region of three or four squares has few places for its star, and each place rules out a lot of the board.
- Look for regions that sit entirely in one row or column. That line's star must then be inside the region, so everything else in the line can be crossed out.
- Turn the same idea round: if a row's free squares all belong to one region, that region's star is in this row, and the rest of the region is out.
- Ask what a star would do before placing it. If a star on a square would cover every free square of some region, row or column, that square can be crossed out, because that region would have no room left.
- Count groups on bigger boards. If two rows fit entirely inside two regions, those regions spend their stars there and the rest of both regions is out. The same goes for three rows and three regions, and for columns.
- Use the corners of a star's reach. A star rules out its eight neighbours as well as its row, column and region, so a region hugging a square from two sides often loses it at once.
Modes and difficulty
The daily board is always a 7×7, the same for everyone, changing at 00:00 UTC; only your first try counts on its leaderboard. Practice lets you pick any size from 5×5 to 9×9, with a new board each time, and a first visit opens on a 5×5 that takes about a minute. The level ladder climbs from 5×5 to 9×9 on fixed boards, and every tenth level cleared for the first time pays a candy bonus. After a solve you can send a friend the same board.
Playing Star Grid on Matsuri
Every board was checked by a program before it reached you: exactly one solution, and a solver that reasons like a person, without guessing, finished it. Harder sizes need harder steps, from a lone free square on a 5×5 to groups of rows and regions on a 9×9. Regions differ by thick borders and by pattern as well as by colour, so the board reads well for colour-blind players. Scores come from the server replaying your moves.
A little history
The puzzle is usually traced to Star Battle, a two-star grid created for the World Puzzle Championship in 2003, and its one-star form has lately spread as the queens puzzle. The idea of pieces that cannot share a line goes back further still, to the eight queens problem of 1848.
In the same series: Logic puzzles
- Sudoku: A fresh sudoku each day, solve it over coffee
- Minesweeper: Clear the board by logic, mind the mines
- Nonogram: Shade by the numbers, a little picture appears
Update log
- · Star Grid arrives: one star in every row, column and colour, none touching. Boards from 5×5 to 9×9, a daily 7×7, a level ladder, hints that explain themselves.
Questions
- Is this puzzle free to play online? Does it work on my phone?
- Yes. It is free with no ads, no download and no signup, and it plays in any browser on phone or desktop or inside Telegram through @MatsuriGamesBot. It is made for a finger: a tap places a star, a second tap crosses it out, and a drag crosses out several.
- What are the rules?
- Place exactly one star in every row, every column and every colour, and no two stars may touch, not even at a corner. The board is solved the moment all the stars are placed with none breaking a rule.
- Is this the star battle puzzle, or the queens game?
- It is the same kind of puzzle: a one-star Star Battle, which many people know as the queens puzzle. The boards, the look and the rules of play here are our own.
- Does every board have one solution? Do I ever have to guess?
- Every board has exactly one solution, and a program has checked that logic alone reaches it, with no guessing. Bigger boards ask for harder reasoning, but a step you can work out is always there.
- What happens if I make a mistake?
- Nothing is lost. Two stars that clash are joined by a line at once, and it costs no points. You can undo as far back as you like, clear the board, or ask for a hint, which takes off whatever cannot stay, shows the next step and says why, for a tenth of the score.
- Is the daily board the same for everyone?
- Yes. The daily is a 7×7, the same board for everyone, so you can rank on the daily leaderboard or send a friend the same board.