About ∞ Tango Unlimited

∞ Tango Unlimited (8tango.com) is a free, browser-based logic puzzle inspired by classic "Sun & Moon" deduction games. Your goal is simple: fill every cell of a grid with one of two symbols — Sun or Moon — while following a small set of elegant rules. No guessing, no luck, just pure reasoning.

What makes Tango different

• Unlimited puzzles — our procedural generator creates a fresh board every time you hit "New Game." You'll never run out of levels to play.
• Four board sizes — from beginner-friendly 4×4 grids to brain-bending 10×10 challenges. Pick the size that matches your mood.
• Guaranteed solvable — every generated puzzle is mathematically verified to be solvable by logic alone. No trial-and-error required.
• Smart hints — stuck on a cell? The hint system tells you which rule to apply and where, so you learn as you play.
• Journey mode — over 200 hand-tuned levels that gradually introduce new techniques, from basic counting to advanced constraint chains.
• Customisable themes — swap Sun/Moon for dozens of icon pairs (cats/dogs, fire/ice, and more). Play in light or dark mode.
• No downloads — runs entirely in your browser on desktop and mobile. Nothing to install.

How puzzles are made

Behind every Tango board is a four-step pipeline: first the engine builds a fully solved grid using pre-computed valid row patterns, then it places "=" (same) and "×" (different) adjacency clues based on the solution, then it strategically removes cells while verifying that the puzzle remains solvable by a rule-based solver, and finally it scores the difficulty based on which solving rules were needed.

The result? Puzzles that range from relaxing one-minute warm-ups to multi-step challenges that require advanced deduction techniques — and every one of them is fair.

Curious about the details? Read the full behind-the-scenes article.

The rules in a nutshell

• Balance: each row and column must contain an equal number of Suns and Moons.
• No triples: three identical symbols can never appear adjacent in a line.
• "=" clue: the two adjacent cells must be the same symbol.
• "×" clue: the two adjacent cells must be different symbols.

That's it — four rules, infinite puzzles. Check the How to Play page for a deeper walkthrough and solving tips.

Who built this

8tango is an independent project built by a small team who love logic puzzles and clean design. The game engine is written in Go (server-side generation, validation, and difficulty scoring) with a pure JavaScript frontend — no heavy frameworks, no bloat.

Not affiliated

8tango is an independent game and is not affiliated with, endorsed by, or connected to LinkedIn or any of its products. "Tango" here refers to a style of logic puzzle, not a trademark.

Get in touch

Feedback, bug reports, or just want to say hi? Email us at [email protected]. We read every message.