The Day Thread Solves Star Battle

Star Battle is a puzzle that has consumed more of my recent hours than I would like to admit. Each puzzle consists of a square grid N units to a side, divided into N regions. In each row, column, and region of the grid, you must place X stars such that no two stars touch. It may sound simple, but the puzzle is anything but. I was introduced to it by the New York Times Puzzle Mania special section released this past December, which included an entire page devoted to it. Will Shortz, long-time NYT Crossword editor, wrote about them there:

“Every once in a while a puzzle comes along that gets me absolutely obsessed. KenKen did that to me when it first came out… The puzzle I can’t stop doing right now is one of pure logic called Star Battle – or, what I think is a better name for it, Two Not Touch. I came across it in Germany in October during the 28th World Puzzle Championship. I picked up a book there titled “Ratsel Dich Schlau und Glucklich” (roughly, Puzzling Yourself Clever and Happy”) that had a section of these… The Book’s puzzles come in three difficulty levels… At first i could barely do the easy ones. There were solving hints, but as I can’t read German, I had to figure everything out for myself.

Slowly, I discovered tricks and methods. When I finished my first medium-level Two Not Touch, I wrote in the margin, “Very satisfying!” The hard Two Not Touch puzzles remained utterly beyond me for a while. Really, I wondered, how does anyone do these? How do you even start?…

What I love about Two Not Touch is the simplicity of the instructions (just two sentences) and the elegance of the constructions.

Star Battle is free to play online at https://www.puzzle-star-battle.com/ in sizes ranging from a 1-star 5×5 grid that can be knocked out in a few seconds to a massive 6-star 25×25 grid that releases special only once a month, to be chewed over repeatedly over the course of weeks. I’ve taken to doing the daily 4-Star puzzle (a 17×17 grid) every day the same way I do the NYT Crossword. If you’re in the market for a new time-waster (can’t imagine why), consider giving Star Battle a try.