Solsticio
A calm daily 6x6 grid of suns and moons: balance every line and never put three alike in a row.
Every day: One 6x6 sun and moon grid generated from the date, the same board on the website and app for everyone. New puzzle: Once a day (each board is computed from the date).
Solsticio is a daily binary logic puzzle in the Takuzu or Binairo family, played with suns and moons. Each day's 6x6 board is generated from the date, so everyone gets the same grid, and every board is checked to be solvable by pure deduction. Each daily page also has a step-by-step solution for after you play.
About Solsticio
Solsticio is a free sun and moon logic puzzle for the browser and Android, made by Carlos Marcos, an independent developer. It belongs to the same family as Takuzu, Binairo and LinkedIn's Tango.
The daily puzzle is computed from the date by a deterministic generator, so there is no server deciding it: the website and the app show the same board to everyone, and the app works offline. Before a board is used, the built-in solver has to finish it without guessing, which guarantees a single solution, and its difficulty is rated by the deduction techniques it needed.
A day's board is a 6x6 grid with a few fixed suns and moons. You tap cells to cycle between sun, moon and empty until every row and column holds three of each and no line has three alike in a row; later puzzles add = and x connectors between cells. A timer runs while you play and you can share your result without the answer.
Every date has its own page with the board and a full worked solution, listing each forced move and the rule behind it, and an archive keeps earlier days. It suits players who enjoy Tango or Binairo and like a short, guess-free puzzle; the Android app adds hundreds of extra levels and a Zen mode.
How to play Solsticio
- Open today's puzzle on the Solsticio home page.
- Tap an empty cell once for a sun, twice for a moon, and a third time to clear it.
- Make sure no row or column has three suns or three moons in a row.
- Balance every row and column with three suns and three moons.
- Fill the last cell with all rules holding to stop the clock and share your time.
Tips
- Two matching symbols side by side force the opposite symbol at both ends.
- When a line already has three suns, every empty cell left in it must be a moon.
- Read the worked solution on the daily page afterwards to learn the techniques you missed.
Questions
Is everyone given the same board?
Yes. The daily board is generated from the date alone, so the website and the app show the same grid to every player.
Will I ever have to guess?
No. Every daily board is checked by a solver that uses only deduction, so it has exactly one solution.
Can I play old puzzles?
Yes. An archive lists past days, and each date's page includes a step-by-step solution.
Is there an app?
Yes, a free Android app with the same daily puzzle plus hundreds of levels and a Zen mode.
Games like Solsticio
Equinox (Puzzleship)
Balance suns and moons in every row and column, never three in a row.
Tango
A small daily grid of suns and moons with balanced lines.
Daily Binairo
One large binairo a day with balanced lines.
Rumba: Binairo Plus Puzzle
A daily binairo with extra clues between cells.
Nunca Quatro (O Globo)
Fill the grid with two symbols, never too many in a row.
yotsu.
A few calm logic puzzles a day, binairo among them.
Alibi
Put every suspect and weapon back in the right room, and the killer reveals itself.
Bearing (Arkai)
Turn, listen, and triangulate two or three hidden sound sources around a 16-point compass.