Logic games that make you think: what each puzzle asks of you

The logic games that make you think hardest are the ones where every answer can be worked out and none has to be guessed: sudoku, minesweeper on a fair board, nonograms, and grid puzzles such as KenKen and Kakuro. Each one asks for a slightly different kind of reasoning. Knowing which kind you enjoy is the quickest way to find the next puzzle you will love — so this guide explains what each game is really asking your head to do.

What makes a logic game a logic game

A logic puzzle gives you a set of rules and a partial picture, and asks you to fill in the rest with certainty. The good ones share three properties.

• One answer. If two solutions fit, the last few moves become a guess, and the puzzle stops being logic.
• Reachable by reasoning. Every step can be justified from what is already on the board. You may need to look hard, but you never need luck.
• Layered difficulty. Easy puzzles yield to one simple move repeated. Hard ones need you to hold several possibilities in mind at once.

Those properties are what make a solve feel earned. It is also why the logic games on BrainBreak each ship with a solver behind them: the solver is used to check a board before you ever see it.

Sudoku: elimination and placement

Fill a nine-by-nine grid so every row, column and three-by-three box holds the digits 1 to 9 once each. It sounds like arithmetic, but there is no adding up at all — the digits could just as well be nine colours. Sudoku is pure constraint reasoning.

Two moves carry most grids:

• Only one digit fits. Take one empty square and rule out everything already in its row, column and box. If one digit is left, it goes there.
• Only one square is left. Take one digit and one box, and ask where the digit could go. If only one square can hold it, it goes there — whatever else that square could have held.

Harder grids ask you to reason about groups of squares: two squares in a row that can only hold the same two digits, for example, rule those digits out of the rest of that row. On BrainBreak the four difficulties are graded by exactly this — which techniques a grid needs — rather than by how many numbers it starts with. Our sudoku tips for beginners walk through the first few in detail.

Minesweeper: local deduction

Each opened square tells you how many of its eight neighbours hide a mine. The reasoning is local: you look at one number and its neighbours, then at two numbers that share neighbours, and work out what must be true of the squares between them.

The classic example is a row of numbers along a straight edge reading 1 2 1, with a row of covered squares beside it. The only arrangement that satisfies all three is a mine in the covered square directly opposite each 1, and none opposite the 2. Once you have seen a pattern like that a few times, you start recognising it at a glance, and the game becomes a mix of quick pattern-spotting and slower, careful reasoning where the patterns run out. Our minesweeper patterns guide collects the common ones.

Traditional minesweeper has one famous flaw: some boards cannot be finished without guessing. Here, every board is checked before you see it, and the numbers alone are always enough to finish, right down to the last square. Your first click is always safe, too. If you are stuck, there is something to work out.

Nonograms: logic with a picture at the end

A nonogram gives you numbers along the edge of each row and column, describing the runs of filled squares in that line, in order. Fill the squares correctly and a picture appears.

The central idea is overlap. A run of three in a line of five can start in three places, but in every one of them the middle square is filled — so you can fill it without guessing. Each square you settle in a row gives you information about the column it sits in, and the puzzle unfolds by bouncing between the two. Every picture on BrainBreak has been checked to be solvable this way, one line at a time.

Nonograms suit people who like sudoku but want something to show for it at the end. They also scale well: a five-by-five is a warm-up, a fifteen-by-fifteen is a proper sit-down.

Quartets: reasoning about categories

Not every thinking game uses numbers. Quartets gives you sixteen words hiding four groups of four, and four mistakes to spend. The logic here is hypothesis testing: you notice a possible group, check whether any word fits two groups, and look for the word that belongs nowhere else before committing.

That last habit is what separates a good solve from a lucky one. Most puzzles have a red herring — a word that looks like it belongs to the obvious group but is needed elsewhere. Spotting the trickiest group early, even if you submit it last, is often the safest way through.

2048: planning under uncertainty

2048 is the odd one out here, because it has randomness: a new tile appears after every move. That changes the kind of thinking it asks for. Instead of deducing a single right answer, you are keeping the board in a shape that stays safe whatever the next tile turns out to be — a biggest tile held in a corner, with a descending chain beside it. It is closer to strategy than to pure logic, and a useful contrast if deduction puzzles start to feel too tidy.

Classic logic puzzle formats worth knowing

Beyond the games above, there is a whole family of pencil-and-paper logic puzzles. They are not on BrainBreak, but if you enjoy sudoku you will probably enjoy some of them.

KenKen

A square grid in which each row and column contains each number once, like sudoku, but with no boxes. Instead, the grid is divided into outlined “cages”, each labelled with a target and an operation, such as 12× or 3−. The numbers in a cage must combine to hit the target. It mixes sudoku-style elimination with a little arithmetic.

Kakuro

Often described as a number crossword. White squares form runs across and down, and each run has a clue giving its total. Fill the runs with digits from 1 to 9, with no digit repeated within a run. Much of the skill is knowing which combinations can make a given total — a two-square run adding to 3, for instance, can only be 1 and 2.

Grid logic puzzles

The “who lives in which house and owns which pet” kind. You are given a list of statements and a grid for cross-referencing every pair of categories, and you mark each combination as possible or impossible until only one arrangement remains. They are excellent practice in tracking what you know for certain versus what you merely suspect.

Futoshiki

Another Latin-square puzzle: each row and column holds each number once, with a few greater-than and less-than signs between neighbouring squares as the clues. The first deductions are simple — a square that must be larger than a neighbour can never be a 1 — and they build from there.

Which logic game should you start with?

All of them are free, need no account and run in a browser on a phone or a computer. If a nonogram sounds like your kind of puzzle, the one below is a good first stop.