Hoshi (Sudoku)

Hoshi is a variant of Sudoku, based around triangles instead of squares.

In a hurry? Jump to: Rules / Tips / Download Free Hoshi Puzzles / Books

Here’s what an easy Hoshi puzzle looks like:

Rules of Hoshi

Normal Sudoku rules apply to Hoshi, but instead of being constrained by rows, columns, and blocks, we have to fill in the puzzle without repeating digits in triangles and lines. 

Here’s what the earlier example looks like once solved:

Below, we've highlighted the six triangles, to make it easier to see those constraints. They are the equivalent of blocks in regular Sudoku:

Here we’ve highlighted examples of different lines, which are the equivalent of rows and columns in the normal version of the puzzle:

You will notice that although the six triangles that comprise the Hoshi grid each contain nine numbers, not all the lines in the puzzle do; some only contain eight. However, the rules still dictate that a line cannot contain duplicate digits. For example, the red line at the bottom only contains eight digits, but it does not contain the digits from 1-8. Instead, there is a 9 but no 7. As long as no digit is repeated, then it’s within the rules.

You will also see that four of the lines in Hoshi cross the hexagonal hole in the middle. In this example, the yellow line is split across the middle, yet still forms a single valid line containing the digits 1-9 once and only once.

Solving Hoshi Puzzles

Hoshi is a variation of classic Sudoku, so if you’ve played Sudoku before, you’re all set to go. If not, be sure to read through our comprehensive three part tutorial – it teaches you everything you need to know to solve regular puzzles, and the same techniques apply in Hoshi.

Here are some additional tips you can use to help with Hoshi:

• Keep an eye on intersections. Because Hoshi is based on triangles and not squares, most cells fall at the intersection of three lines, not two like in regular Sudoku. You get a whole extra dimension to help you eliminate candidates!
• When you place a digit, it’s worth going around all six main triangles to look for knock-on effects. The multiple intersections combined with the triangles themselves can often allow you to fill in the same digit all the way around the puzzle, compounding the success of finding that one original.
• Use candidates / notes. Just as with regular Sudoku, writing in small candidate numbers as notes is helpful, and indeed necessary in harder puzzles. 

Try Hoshi Yourself

Are you ready to have a go at Hoshi yourself? We’ve put together free taster pack with a couple of easy starter puzzles, and a couple of harder ones, too. Download the PDF below. Solutions are included so you can check your results.

Click Here To Download The Taster PDF

Where To Play

Want to play Hoshi? We’ve got you covered, we have books of puzzles ready and waiting to be solved.

Puzzle Weekly Presents: Hoshi is a collection of 120 puzzles set over seven levels of difficulty. Grab a copy here.

Got a Kobo? We’ve got Hoshi puzzles for that too!  Hoshi for Stylus Devices presents 100 puzzles over five levels, and is designed especially for Kobos with stylus. Find out more here.