To keep my introduction brief, let me just say that I've been a fan of
Japanese pencil puzzles, particularly the ones created and/or published by
Nikoli since early 2007, and own
a variety of these puzzle books. However,
it's not always easy to find descriptions of the rules in English,
especially for less popular or well-known games, and I've created this page
to help solve that problem. Since I don't know Japanese myself, I'm relying
mainly on a few sources to write my descriptions: 1) English instructions
from Nikoli, when available, 2) other English instructions available,
normally found online, 3) Babel Fish
translations of Japanese instructions, mainly found online, and
4) my own interpretation of the rules by trial and error. I plan to add
rules to this page in basically that order above, referencing my sources when
I can, but puzzles I have in books will get added before ones I haven't seen.
Feel free to contact me if you
find these short rules helpful or if I have made any mistakes here. In the
case of mistakes, please send me corrections if you can so that we can all
have access to correct rules. Also let me know if the rules are unclear, and
I can try to rewrite the descriptions if enough people have trouble
understanding them. Thank you very much for any help you can provide.
Thanks to GLmathgrant for some rules clarifications/corrections.
P.S. -- Here's a link back to my hobbies page if
you got here without going through it first.
Quick links to 43 brief puzzle rules: Akari / Light Up, Bag, Barns, Block Puzzle, Country Road, Creek, Fillomino, Goishi Hiroi, Gokigen Naname, Hashiwokakero / Bridges, Heyawake, Hitori, Hukumenzan, Hotaru Beam, Ice Barn, Inshi no Heya, Kaero, Kakuro / Cross Sums, Kanaore, Kin-Kon-Kan, Kurodoko (was Kuromasu) / Where Is Black Cells, LITS (was Nuruomino), Makkuro, Masyu, Mochikoro, Mushikuizan, Nansuke, Noridoko, Number Link, Nurikabe, Reflect Link, Ripple Effect, Shikaku / Divide by Box, Shimaguni, Slalom, Slither Link, Stained Glass, Sudoku, Tatamibari, Tatebo-Yokobo, Tentai Show, Yajilin, Yajisan-Kazusan,
Place light bulbs (circles) so that every square in the grid is lit or contains a light bulb. Numbered cells indicate how many light bulbs are next to it, horizontally and vertically. Light bulbs may go in any white/empty cell and illuminate all the cells vertically and horizontally from it to a black cell or the edge of the board, whichever comes first, but no light bulb may illuminate any other light bulb.
Source: Nikoli Penpa Mix 2, 3, 4; see also Light Up on Wikipedia
Draw a single loop without crossings or branches along the grid lines. Every numbered cell must be inside the loop. Numbered cells can see the specified total number of cells vertically and/or horizontally (including itself) before reaching a wall of the loop.
Source: Bag on Wikipedia; clarification by GLmathgrant
Draw a single loop without crossings or branches through the centers of the cells in the grid, passing through every cell in the grid. Lines that enter a gray area cannot change direction until the leave the gray area. Lines are only allowed to cross inside the gray areas. Dark lines in the grid are walls and cannot be crossed by the loop.
Source: Babel fish translation of Barns; example in (for example) Puzzle Communication Nikoli 117 with trial-and-error
Divide the grid into pieces that contain permutations of the symbols (numbers, letters, or Japanese kana) of the specified words.
Source: Babel Fish translation of Nikoli's Block Puzzle rules; clarification by GLmathgrant
Draw a single loop (road) through the grid where the line passes horizontally or vertically through the center of cells without crossing, branching, or going through the same cell twice. Countries (bold outlined areas in the grid) with numbers have the given number of cells used by the road, and countries without a number must have 1 or more cells used by the path. The road may only enter a country once and exit it once. Adjacent unused cells must not be in different countries.
Source: Country Road on Wikipedia; clarification by David Olmsted
Paint cells black such that numbered intersections have the given number of black cells around them and all white, unpainted cells form a single connected area (the creek).
Source: Babel fish translation of Creek; example in Nikoli Puzzle Box 8 with trial-and-error
Fill in all empty cells by dividing the grid into blocks (groups of cells connected horizontally and/or vertically with the same number) so that each block has the same area/size as the number in it and blocks of the same size do not touch each other horizontally or vertically.
Source: Nikoli Penpa Mix 2, 3, 4; see also Fillomino on Wikipedia
Starting from any stone on the board, travel in vertical and/or horizontal lines to pick up all of the go stones by numbering the order in which they are removed from the board. You may only change direction when you pick up a stone, but may not go back in the direction from which you came, and if you travel over a spot where a stone was picked up (numbered), you may not change direction at that point (the stone is no longer present).
Source: Google Translate and Babel Fish translations of Nikoli's Goishi Hiroi Rules
Draw a diagonal line in every cell in the grid such that numbered intersections have the given number of lines extending from that intersection and lines do not form a closed loop.
Source: Gokigen Naname on Wikipedia
Connect all of the islands together by drawing bridges vertically or horizontally between them. The number on each island indicates the number of bridges connected to that island, there can be no more than two bridges connecting a pair of islands, and the bridges may not cross each other.
Source: Hashiwokakero on Wikipedia
Paint cells black in each room (bold outlined areas in the grid) so that rooms with a number have that many painted cells in them, painted cells are not connected, white cells are not separated by painted cells, and white cells do not span more than two rooms in a straight line.
Source: Nikoli Penpa Mix 2, 3, 4; see also Heyawake on Wikipedia
Paint cells black such that numbers appear no more than once in each row and column. Painted cells must not touch horizontally or vertically, and white (unpainted) cells must create a single connected area not separated by painted cells.
Source: Nikoli Penpa Mix 2, 3, 4; see also Hitori on Wikipedia
Draw lines in the grid to create a single, connected network joining all circles (on intersections of grid lines). The network may cross or branch only at circles. Dots on circles indicate where a line of the network connects to the circle. Numbers in circles indicate the number of turns the line makes after leaving the dot and connecting to another circle.
Source: Hotaru Beam on Wikipedia
Each different character in the equation represents a different number. Replace the characters with numbers to solve the equation. Zero will not be a leading digit, and numbers that appear in the equation may also be used as a character.
Source: Google Translate translation of Nikoli's Hukumenzan Rules
Draw a single loop through the grid from IN to OUT that follows the directions of the arrows. Lines that enter a gray area cannot change direction until they leave the gray area. Lines are only allowed to cross inside the gray areas. The loop must go through every gray area at least once.
Source: Babel fish translation of Ice Barn; example in Nikoli Puzzle Box 8 with trial-and-error; clarification by GLmathgrant
Fill all the cells in the grid with numbers from 1 to 9, inclusive, such that no number appears twice in any row or column and the product of the digits in each room (bold outlined areas in the grid) equals the given number in each room.
Source: Inshi no Heya on Wikipedia
Move letters on the board so that each room (bold outlined areas in the grid) contains all appearances of one letter -- all of the As are in one room, all of the Bs are in another room, etc. Movement of letters is indicated by lines that pass through the centers of boxes, bending at right angles as needed, with an arrow at the end indicating the destination cell. Lines cannot cross or branch.
Source: Babel fish translation of Kaero; example in (for example) Puzzle Communication Nikoli 117 with trial-and-error
Place a number from 1 to 9, inclusive, in each cell so that the sum of the numbers in each block (vertical column or horizontal row of connected white cells) is equal to the number at the top or left of that block cells and each number is used no more than once in each block.
Source: Nikoli Penpa Mix 2, 3, 4; see also Cross Sums on Wikipedia
Fill the grid with the given (Japanese) words. Each word has a number and direction; the word starts in the matching numbered cell in the grid and begins extending the direction specified. Each letter/character must be placed horizontally or vertically adjacent to the last. Some letters/characters may be used by more than one word.
Source: Example in Nikoli Puzzle Box 6, 7, 8 with trial-and-error
Place diagonal lines in cells (mirrors) such that each room (bold bordered area in the grid) contains exactly one mirror, and letter-number pairs at the edges of the grid can be connected by straight lines that bounce of the same number of mirrors as the number in the letter-number pair. For example, B2 at one edge must connect to the other B2 by straight vertical and horizontal lines (passing through the centers of the cells) that bounce off of 2 mirrors in the grid.
Source: Kin-Kon-Kan on Wikipedia
Paint cells black such that each numbered cell can see the specified total number of cells vertically and/or horizontally (including itself) before reaching black cells or edges of the grid. Black cells may not touch horizontally or vertically, and all white cells must create a single connected area not separated by black cells. Numbered cells may not be black.
Source: Kuromasu on Wikipedia
Color four consecutive squares (tetrominoes) in each area surrounded by bold lines such that similarly shaped or rotated tetrominoes do not touch except possibly at corners, the colored squares form a single connected area, and the colored squares do not form areas of 2x2 or larger.
Source: Nikoli Penpa Mix 4; see also LITS on Wikipedia
Fill the crossword-like grid with numbers according to the given clues, which are numbered and grouped by answers that read across (left to right horizontally) and answers that read down (top to bottom vertically). Clues are given in terms of the answers to other clues; for example, using a sample game from Nikoli, 1 down minus (ひく) 8 across, 1/2 (2分の1) of 4 down, 7 down times (倍) 8, 2 across plus (たす) 6 down.
Source: Example in Nikoli Puzzle Box 6, 7, 8 with trial-and-error
Draw a single loop without crosses or branches with lines extending horizontally or vertically through the centers of the cells. The loop must include all cells with white and black circles. White circles indicate that the path goes straight through the cell and makes a 90-degree turn in the cell before it, the cell after it, or both. Black cells indicate that the path makes a 90-degree turn inside the cell, with the path extending straight for two cells before and after it.
Source: Nikoli Penpa Mix 2, 3, 4; see also Masyu on Wikipedia
Paint cells black to create rectangular and/or square rooms of white cells with at most one number per room and size/area equal to the number in each room. Rooms may not touch vertically or horizontally, but must touch at least one other room diagonally so that all rooms are connected. Black cells may not form areas of 2x2 cells or greater.
Source: Mochikoro on Wikipedia; clarification by GLmathgrant
Each square in the equation represents a single digit, 0-9. Replace the squares with numbers to solve the equation. Zero will not be a leading digit, and numbers that appear in the equation may also be used in the square(s).
Source: Google Translate and Babel Fish translations of Nikoli's Mushikuizan Rules
Place all of the given numbers into the crossword-like grid. (This is like a crossword with numbers, where you have all the answers and have to figure out where they belong, instead of knowing where the answers belong and having to figure them out.)
Source: Example in Nikoli Puzzle Box 6, 7, 8 with trial-and-error
Paint cells black such that each numbered cell can see the specified total number of cells vertically and/or horizontally (including itself) before reaching black cells or edges of the grid. Black cells must form 2x1 or 1x2 areas, and these areas may not touch horizontally or vertically. All white cells must create a single connected area not separated by black cells. Numbered cells may not be black.
Note: this seems like kuromasu/kurodoko, just with 2x1 and 1x2 black areas instead of 1x1 black cells, but I may be missing something.
Source: Example in Puzzle Communication Nikoli 117, 118 with trial-and-error
Connect pairs of the same number together with lines that pass horizontally and/or vertically through the centers of cells. Lines cannot cross or branch off, and cannot go through the same cell twice.
Source: Nikoli Penpa Mix 2, 3, 4; see also Number Link on Wikipedia
Paint cells black so that the grid is full of white areas, each with a single number and size equal to that number, separated by black cells (walls) that are all connected and do not form 2x2 or larger areas. Numbered cells must not be painted black, and white areas must be separated from each other horizontally and vertically by black walls.
Source: Nikoli Penpa Mix 2, 3, 4; see also Nurikabe on Wikipedia
Draw a single loop without branches by drawing lines horizontally and/or vertically through the centers of cells. If a cell has a plus sign in it, two lines intersect in it; these are the only places lines may intersect. Cells with triangles in them reflect the line at right angles, and all triangles must be touched by the lines. Numbered triangles indicate the total number of cells (including the triangle's cell) that the beam travels horizontally and vertically before changing direction.
Source: Babel fish translation of Reflect; example in Nikoli Puzzle Box 7, 8 with trial-and-error
Number all cells in each room (bold outlined areas in the grid) such that each room contains consecutive numbers starting from 1, and if a number appears more than once in a row or column, they are separated by at least that number of cells. For example, a room with 4 cells must contain the numbers 1, 2, 3, and 4, and two 3s in the same row must be separated by 3 or more cells.
Source: Nikoli Penpa Mix 2, 3, 4; see also Ripple Effect (puzzle) on Wikipedia
Divide the grid into rectangles and/or squares (boxes) such that each box drawn contains one number and that number is the size (area) of the block.
Source: Shikaku on Wikipedia
Shade in a polyomino in each area surrounded by bold lines such that no two polymoinoes touch except possibly at corners, no two touching regions contain polyominoes of the same size, and a numbered region contains a polyomino of that size.
Source: GLmathgrant's explanation of Shimaguni; examples in Puzzle Box 9
Draw a single loop, starting and ending at the circled number, without branches by drawing lines horizontally and/or vertically through the centers of cells. The circled number indicates the total number of dashed lines (gates) on the board. The loop must pass perpendicularly once through each gate, and numbered gates indicate the order in which the gates are passed. Unnumbered gates may be crossed in any order.
Source: Slalom; examples in Puzzle Box 9, Puzzle Communication Nikoli 117, 118
Draw a single loop without crossings or branches by connecting adjacent dots with horizontal or vertical lines. If a cell has a number in it, then it must have exactly that number of lines surrounding it. If a cell is empty, then it may have any number of lines (from 0 to 3).
Source: Nikoli Penpa Mix 2, 3, 4; see also Slitherlink on Wikipedia
Paint areas black according to the rules indicated by the color of the circles at their intersection: a black circle means more of the neighboring areas touching it are painted than unpainted; a white circle means more of the neighboring areas touching it are unpainted than painted; a gray circle means there are an equal number of painted and unpainted neighboring areas touching it.
Source: Stained Glass on Wikipedia
Place a number from 1 to 9, inclusive, in each cell such that every row, column, and 3x3 block (outlined in bold) contains all of the numbers from 1 to 9 only once.
Source: Nikoli Penpa Mix 2, 3; see also Sudoku on Wikipedia
Divide the grid into rectangles and/or squares (boxes) such that each box contains one symbol (+, -, or |), boxes with a + are square (height and width are equal), boxes with a - are wider than they are tall, boxes with a | are taller than they are wide, and no four boxes share the same corner.
Source: Tatamibari on Wikipedia
Place a vertical or horizontal line through the center of every cell such that shaded numbered cells have the given number of horizontal and/or vertical lines extending out of it and unshaded numbered cells have a line with length equal to the given number passing through it horizontally or vertically.
Source: Tatebo-Yokobo on Wikipedia
Divide the grid into blocks (groups of cells connected horizontally and/or vertically with the same number) so that each block contains a circle, and the block is symmetric under a 180-degree rotation about the circle (the shape looks the same if you rotate it 1/2 turn). Blocks with black circles are then painted black, while blocks with white circles are left unpainted. The result should be a picture.
Source: Nikoli Puzzle Cyclopedia
Paint cells black in the grid such that each row and column has a total number of painted cells equal to the number at the left and top of the grid. Blocks in the grid (bold outlined areas in the grid) must be either fully painted or fully unpainted. The result should be a picture.
Source: Nikoli Puzzle Cyclopedia
Draw a single loop through the grid where the line passes horizontally or vertically through the center of cells without crossing, branching, or going through the same cell twice. The line cannot pass through numbered cells, which indicate how many black cells are in the direction of the arrow in that cell, or black cells, which cannot touch each other horizontally or vertically. Every cell the loop doesn't pass through must either be a numbered clue cell or a black cell.
Source: Nikoli Penpa Mix 3, 4; see also Yajilin on Wikipedia; clarification by GLmathgrant
Paint cells black such that numbered cells indicate the number of black cells in the direction of the arrow in those cells. Black cells may not touch horizontally or vertically, and all white cells must create a single connected area not separated by black cells. Numbered cells must be painted black if they contain false clues, but numbered cells painted black do not necessarily contain false clues.
Source: Yajisan-Kazusan on Wikipedia
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