Nonogram

Nonograms, also called Picross or Hanjie, are grid-shading logic puzzles in which solvers fill in a grid based on clues for each row and column in order to create a picture. Popular in video game form, nonograms are one of the only puzzle type to have a dedicated game in the Super Mario franchise.

Background

A completed nonogram of the letter "W"

Nonograms were invented by two different people in Japan in 1987, independently from one another. The first was Non Ishida, a graphic editor who got the idea for the puzzle after winning a design competition in which they made images using lights in a skyscraper that had been turned on or off. The other was Tetsuya Nishio, a puzzle-writer, who began publishing them in a local magazine.

Despite both having a possible claim, Ishida won out on the global market by bringing their 'Window Art Puzzles' to English puzzler James Dalgety, who renamed them as Nonograms (a portmanteau of [Non] Ishida and Dia[gram]). Dalgety got them published in The Telegraph, from which the puzzles rose in popularity, becoming a weekly publication. From there, the puzzles drifted elsewhere in the world, including being imported back to Japan to be published in major newspapers, and to collection books to be sold worldwide. Eventually, when Non Ishida desired to keep the name 'Nonogram' for their own work, outside publications had to find other names for their puzzles, which included 'Paint by Numbers' and 'Griddlers'.

The puzzle's popularity also extended to the digital world, with the game company Nintendo hopping on the bandwagon with eleven puzzle games called 'Picross' (short for Picture Cross) published for their Gameboy and Super Famicom systems. Of those eleven, one was released outside of Japan: Mario Picross, which featured Nintendo's primary IP and became quite popular. Since then, Nintendo handheld consoles have had a steady stream of Picross games, thanks to developer Jupiter Corporation, who have released games for every handheld Nintendo console since the Gameboy. The most recent Jupiter-made Picross game, Picross S8, was released for the Nintendo Switch in September of 2022.

Puzzle Application

Core Rules

Nonograms in general have two primary rules for construction and solving. First, all shaded cells in the solution must be indicated both by the clues in their row and by the clues in their column, allowing every cell to be cross-checked. These clues are presented in the same order that they appear in the grid, from left to right or top to bottom. Secondly, when a 'run' of cells (any amount of 1 or greater) is clued to be shaded in a row or column, that run must have at least one unshaded cell between it and the next run in the same row/column. For example, a clue of '4 3' would result in a run of four shaded cells, then at least one unshaded cell, followed by a run of three shaded cells.

As hunt puzzles like to break rules, these two would theoretically be good rules to watch out for exceptions to. However, it is extremely rare for a puzzle to break both rules, as removing both the ability to cross-check one's answers and the knowledge that spaces will be present (at least without telling solvers this) massively increases the difficulty of a puzzle, and is more likely to produce either an unfun or impossible-to-solve puzzle.

Solutions

One way that hunt puzzles can play with the conventions of a Nonogram without breaking the core rules is by experimenting with the results of a puzzle. Most Nonograms result in a picture, something clearly recognizable to solvers upon completing the puzzle, but not necessarily while mid-solve. Given the lack of limit on size or shape for these puzzles, hunt puzzles may choose to have a puzzle result in letters, words, or abstract shapes depending on what the rest of the puzzle is like. Letters/words are common for puzzles that either need additional instructions post-nonogram, or simply want to spell out a final answer rather than show it pictorially. Abstract shapes, on the other hand, are commonly used in puzzles that contain either multiple nonograms, or multiple grids as a whole. Abstract shapes can be used as overlays for other puzzle components, or possibly brought together with other shading-based logic puzzles to create larger images in the style of a flat-edged Jigsaw Puzzle.

Variants

Color Nonograms

A large-scale Color Nonogram depicting a pair of parrots.

Colored Nonograms are visually fairly similar to regular black-and-white Nonograms, at least in terms of involving the same kinds of grids and having their clues lined up in rows and columns. The most striking difference is obviously that they use color, which means that puzzle setters can create much more detailed and vibrant solutions that would not be possible to depict (or at least not possible to depict as nicely) in black-and-white. There's a hidden change in this variation as well, though. Due to clues having multiple colors, there are many more exceptions to the 'space between runs' rule.

In Color Nonograms, clues only require an unshaded cell between runs if they're colored in the same way. If the aforementioned '4 3' clue was in a Color Nonogram, it would only function the same way if both numbers were, say, red. If one were red and the other were blue, the puzzle may have four red cells, followed directly by 3 blue cells, and it wouldn't be breaking any rules. This is because the change in colors provides a delineation between runs that normally only a blank cell would be able to achieve. As a result of this, Color Nonograms are often considered to be much more difficult than regular Nonograms. In addition, the fewer unique colors a Nonogram uses, the more difficult the puzzle can become, particularly if they're used in relatively equal amounts. This is because large, diverse color palettes can often allow for increased cross-checking, making some Color Nonograms easier than their uncolored equivalents.

Lined Nonograms

Three different variations on the same cat Nonogram, using a grid, straight lines, and curved lines.

Lined Nonograms are an alternative to using a grid as the main solving field. Instead, a Lined Nonogram will involve intersecting lines at various angles (or curved lines), crossing to create a series of isolated regions within the space. Then, since these puzzles don't have distinct rows or columns, clues are attached to the lines themselves, indicating the number of shaded regions border the line on either side of it (indicated by whichever side of the line the clues are found).

The main purpose of this variation is to produce solutions that allow for more shape detail and region variation. In a normal Nonogram, the setter is essentially limited to doing pixel art, with no individual shaded region differing in size or shape from any other shaded region. With Lined Nonograms, regions vary drastically, allowing for the setter to create whatever sizes/shapes that they want. This is especially true for curved-line Nonograms, which aren't limited to polygons when designing a final shape, and can allow for the only truly smooth images in nonograms.

The tradeoff with the freedom of artistic expression in Lined Nonograms is that they can become much more difficult to solve if the setter decides to go into too much detail. Small regions are often accompanied by many other small regions, making for a lot more options for shadeable areas. More options means more ambiguity, and can create overly frustrating puzzles to solve.

Strategy

• In a standard nonogram, a row or column with N clues that sum up to M must take up at least M+N-1 squares total (because in between clues there must be at least one empty space).
  • Continuing from above, if the total grid size is, say, R columns wide, then a row that takes up S squares (using the above calculation) means that it has R-S degrees of "flexibility". If this is 0, then great - the entire row is specified! If this is larger, you can still pencil in certain regions if the clues are large enough (specifically, you can shade some cells if there is an individual clue greater than the total flexibility).
• It's often helpful to get a break-in at an edge, because the first/last clues can give a large amount of information allowing the solver to progress inward the puzzle. You can use neighboring rows and columns to rule out positions of long runs near the edge as well.
• As a meta-strategy, many nonograms solve to an image, so it may be possible to recognize what the nonogram is drawing early (possibly filling in regions non-logically). But make sure to keep a copy of your work (that you know is logically sound) in case you mess up!

Notable Examples

Played Straight

• Much Paint, Many Numbers (MITMH 2002) (web) - A Color Nonogram with a very diverse palette. The puzzle itself is a bit tricky to solve, but otherwise there are no twists.
• Going Nuts (MITMH 2003) (web) - A very large (66x77) black-and-white Nonogram that may take solvers a good while to solve. Complicated by the fact that it doesn't make any recognizable images, but otherwise there are no tricks. Solvers will later realize that Click to revealthey need to cut the solution up and rearrange it to form an image as their final answer.

Notable Twists

• Paint by Fractions (MITMH 2005) (web) - A Nonogram that introduces the concept of 'half-filled cells'. While it only deals with diagonal slices, and gives some good, clear instructions on the different ways to fulfill the clues, it's still a tricky twist to the genre that may catch solvers off-guard.
• Paint-by-Symbols (MITMH 2013) (web) - While the Nonogram itself is straightforward, it's complicated by the fact that the clues are not numerical. Instead, they're represented by abstract symbols that solvers have to correspond to particular numbers Click to reveal(1-21, and 50) in order to solve the puzzle.
• Moral Ambiguity (MITMH 2019) (web) - Another puzzle involving half-filled cells, but in a different way. Click to revealTying into the title, a half-fill is equivalent to shading a cell grey, rather than fully black. As a result of this complication, clues of any number could theoretically be made up of double the number of grey squares rather than the shown number of black ones.

See Also

• List of Nonograms