How to Play Tango

Tango is a logic puzzle played on a square grid. Your job is to fill every empty cell with one of two symbols — ☀ (Sun) or 🌙 (Moon) — using nothing but deduction. If you've ever played Sudoku, you'll feel right at home: the rules are simple, but the chains of logic they produce can be surprisingly deep.

The Four Rules

1. Balance

Every row and every column must contain exactly the same number of Suns and Moons. On a 6×6 board that's 3 of each; on a 4×4 it's 2 of each; on an 8×8 it's 4 of each; on a 10×10 it's 5 of each.

This is the most fundamental rule. Once a row has its maximum of one symbol, every remaining blank in that row must be the other. Keep a mental count as you go.

2. No Three in a Row

You can never have three or more identical symbols next to each other in a row or column. Two in a row is fine; three is not.

✅ ☀ ☀ 🌙 ☀ 🌙 🌙 (pairs are fine) ❌ ☀ ☀ ☀ 🌙 🌙 🌙 (three Suns in a row — not allowed)

This means that whenever you see two identical symbols adjacent, the cells immediately before and after that pair must be the opposite symbol.

3. "=" Clue (Same)

An "=" symbol between two adjacent cells means those cells must contain the same symbol. If one is a Sun, the other must be a Sun too.

4. "×" Clue (Different)

A "×" symbol between two adjacent cells means those cells must contain different symbols. If one is a Sun, the other must be a Moon.

Controls

Tap / Click an empty cell to cycle through: Empty → Sun → Moon → Empty.
New Game generates a fresh random puzzle.
Hint highlights the next logically forced cell and tells you why.
Undo reverts your last move.

Board Sizes

4×4 (Easy) — 16 cells, great for warming up. Most puzzles solve in under a minute.
6×6 (Classic) — 36 cells, the flagship size. Satisfying chains of deduction without being overwhelming.
8×8 (Challenge) — 64 cells. More room for complex clue interactions and deeper reasoning.
10×10 (Expert) — 100 cells. The ultimate test. Expect some puzzles to require every technique you know.

Step-by-Step Solving Approach

Scan the clues first. Any "=" or "×" where one side is already filled gives you a free cell.
Count each row and column. If a line is nearly full of one symbol, fill the rest with the other.
Hunt for pairs. Two identical symbols next to each other force their neighbours.
Look for sandwiches. A _ A means the blank must be the opposite.
Chain clues together. Filling one cell often triggers another clue, which triggers another, and so on.
Use both axes. If a row is stuck, check the column instead.
Try elimination. On hard boards, hypothesise a symbol and see if it leads to a contradiction.

For more advanced techniques, check the Strategy Guide.

Difficulty Levels

Every puzzle has an automatically computed difficulty score based on which logical rules are needed to solve it:

Easy — basic counting and clue reading.
Medium — triple prevention and gap fills.
Hard — edge patterns and clue chain reasoning.
Very Hard — constraint enumeration across overlapping clue groups.

Journey Mode

If you prefer a structured experience, Journey mode offers over 200 curated levels that ramp up gradually. It starts with gentle 4×4 tutorials and progresses through increasingly tricky 6×6 and 8×8 boards. Each level awards up to three stars based on your completion time.

Red Highlights = Rule Violations

If a cell turns red, it means your placement violates one of the four rules. Fix the violation to continue. The game won't mark the puzzle as complete until every cell is correct.