Getting started with logic puzzles

Every puzzle on Point Paper is a small, closed world with a handful of rules and exactly one way to satisfy them all. You don’t need maths, trivia or a good memory. What you need is the habit of asking one question over and over: what must be true here? This guide explains how to build that habit, which puzzle to start with, and how to use the tools on the site without spoiling the fun.

Which puzzle to try first

The five games use different kinds of reasoning, so it’s worth trying each once before settling on a favourite.

• Halves has the shortest rules: discs and rings, never three alike in a row, half of each in every line. An easy 6×6 grid takes a few minutes and teaches the core idea of every logic puzzle, which is spotting a square that has only one possible value.
• Nonograms are the most rewarding for visual thinkers: you work row by row, and a picture appears at the end. Start with a 5×5 or 10×10 Easy grid.
• Sudoku is the one most people know. Gentle puzzles need only the two simplest techniques, so they are a good way to learn to scan a grid.
• Inequalities is a small number square with signs between the squares. It feels like a sudoku that you can finish over a cup of coffee.
• Star Battle is the most spatial of the five. Try it once you are comfortable marking squares as empty, because that is most of the work.

Each game page shows the rules in full, and How to play covers the controls. The daily puzzles on the front page get harder through the week: Monday and Tuesday are the gentlest days.

You never need to guess

Before a puzzle is published here, a program proves it has one solution, and a second program solves it step by step using only techniques that can be explained. That has a practical meaning for you: at every moment there is at least one square whose value can be worked out from what is already on the board. If you find yourself guessing, you have missed something, and the missing step is usually simpler than you think.

Guessing is also expensive. A wrong guess can survive for a long time before it causes a contradiction, and by then it is hard to tell which entries came from it. Working only with certainties keeps every entry on the board trustworthy.

Start where the rules squeeze hardest

Beginners often scan the grid from the top left. It works better to look for the places where the rules leave the least freedom: a row that is almost full, a region that is tiny, a nonogram clue that nearly fills its line, a pair of equal symbols with a gap between them. The fewer possibilities a place has, the sooner one of them is forced.

That small example contains the whole method. You did not try anything: you read a rule, looked at a spot where it applied, and wrote down the only thing that could go there.

Write down what can’t be, not only what must be

Much of the progress in a logic puzzle is negative knowledge. In a nonogram or a star battle, marking a square as empty is as valuable as filling one, because it shrinks the space the remaining clues have to fit into. In sudoku and inequalities, notes (small candidate digits) do the same job. Keep your marks honest: only record what you have proved, and a glance at the board will tell you the true state of the puzzle.

How to use hints without spoiling the puzzle

The Hint button on Point Paper does not fill in a square. It describes one step that follows from your current board, highlights the squares involved and names the reasoning. Try to finish the step yourself from the explanation; if you still can’t see it, Reveal applies it. A few habits make hints teach you more:

1. Ask for a hint only after you have looked at the board for a minute without finding anything.
2. Read the explanation, then look away from the highlighted squares and find a similar pattern elsewhere.
3. If the hint says your board already contains a mistake, use Check to see which entries don’t match the solution, or undo back to a point you trust.

The finished-puzzle screen shows how many hints and reveals you used, but nothing is lost by using them. The count is there so you can see yourself needing fewer of them over time.

When you are stuck

Every solver hits walls. Before reaching for a hint, run through a short checklist:

• Revisit each rule in turn and ask where it is closest to being forced.
• Look at lines and regions you have ignored for a while; recent entries may have changed them.
• Count. Many hard steps are really arithmetic: how many stars, discs or filled squares are still missing, and how many places are left for them.
• Take a break. Pause hides the board and stops the clock, and a fresh look often shows the step at once.

Keep going

Each game has its own guide with the techniques our solver uses, in the order the difficulty levels introduce them. Once you know the names of the patterns, you will start seeing them everywhere, and the harder levels open up. Every puzzle can also be printed from its page if you prefer to solve with a pencil.