List of Snake variants

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There are a lot of Snake variants. In fact, there had been three occasions of Serkan Yürekli's Snake Variations Contest before. WPC 2017/Round 11 was a round solely consisted of Snake variants. Refer to Snake for the standard definition of the word "snake" in this article. Rules are slightly modified to unify how the rule statements start.

Striped Snake[edit]

Striped Snake Example.png Striped Snake Example Solution.png

First appeared on the IPST 2004, written by Andrey Bogdanov (Russia). [1]

Place a snake in the grid. The snake consists of neighbouring cells of two alternating colours. Numbers to the right show the number of grey cells in that row. Numbers below the grid show the number of black snake cells in that column.

(Rules from 2011 UK Nationals IB, and example from janko.at)

Snake BY[edit]

Snake BY Example.png Snake BY Example Solution.png

First appeared on Forsmarts Issue 29 (2006).[2] Invented by Vladimir Portugalov (Belarus).

Place a snake in the grid. Each outlined region must contain exactly 3 cells occupied by the snake. The regions that contain the head and the tail of the snake are marked by grey colour.

(Rules and example from Forsmarts booklet)

  • Sometimes the name Regional Snake is given to a variation of Snake BY where (i) heads and tails are given and (ii) solvers must determine the number of cells in each region that are occupied by the snake (3 in the original). For example, a puzzle from WPC 2018/Round 11.

Persistence of Memory[edit]

Persistence of Memory Example.png Persistence of Memory Example Solution.png

Invented by Serkan Yürekli. First appeared on Oğuz Atay Puzzle Contest 5 (2009).

Place a snake in the grid. The path must use at least one cell from each outlined and shaded region. If two or more regions have the same shape and orientation, then the path must go through these regions exactly in the same way, including the points where it enters and leaves these regions.

(Rules and example from WPC 2019 IB)

First Seen Snake[edit]

First Seen Snake Example.png First Seen Snake Example Solution.png

First appeared on Puzzle Jackpot [3] in 2011. The author was Serkan Yürekli (Turkey).

Serkan's inspiration for the inclusion of First Seen rule comes from Andrey Bogdanov's First Seen Coral. [4]

Place a Snake in the grid. The numbers outside the grid indicate the lengths of the first snake segment in that row or column.

(Rules and example from WPC 2018 IB)

True-False Snake[edit]

True-False Snake Example.png True-False Snake Example Solution.png

First appeared on 2013 UK Nationals. [5] Author of the puzzle was Prasanna Seshadri (India).

Place a Snake in the grid. Additionally, the numbered arrows in the grid indicate the number of cells the snake visits in the direction of the arrow. If the snake does not pass through a clue cell, then that clue is true, otherwise, it must be false, i.e. cannot be true.

(Rules and example from WPC 2017 IB)

Regional Snake[edit]

Regional Snake Example.png Regional Snake Example Solution.png

First appeared on WPC 2013/Part 7. Author of the puzzle is currently unknown.

Place a snake in the grid. Numbers in each of the regions surrounded by thick lines denote the number of cells occupied by the snake in that region.

(Rules and example from WPC 2013 IB)

All or None Snake[edit]

All or None Snake Example.png All or None Snake Example Solution.png

First appeared on WPC 2018/Round 5. Author of the puzzle was Deb Mohanty (India).

Place a snake in the grid. Additionally, if one instance of a letter is part of the snake, all instances of the letter are part of the snake. Length of the snake is given.

(Rules and example (Length=23) from WPC 2017 IB)

BOA Snake[edit]

BOA Snake Example.png BOA Snake Example Solution.png

First appeared on WPC 2018/Round 5. Author of the puzzle was Amit Sowani (India). Can be seen as Dutch Snake with orientation given.

Place a snake in the grid. Additionally, the head and tail are defined as H and T. Traveling from H to T, the Snake behaves differently at each letter. It goes straight through all Os. It turns clockwise at all As and anti-clockwise at all Bs.

(Rules and example from WPC 2017 IB)

Semitransparent Snake[edit]

Semitransparent Snake Example.png Semitransparent Snake Example Solution.png

First appeared on WPC 2018/Round 5. Author of the puzzle was Petr Lichý (Czech Rep).

Place a snake. Numbers outside the grid indicate the number of snake cells in that row/column. However, every time the snake goes through 4 or more cells in a straight line, every fourth cell along that line is invisible and is not counted.

(Rules and example from WPC 2018 IB)

Double Snake[edit]

Double Snake Example.png Double Snake Example Solution.png

First appeared on WPC 2018/Round 10. Author of the puzzle was Petr Lichý (Czech Rep).

Place two snakes. Two snakes can touch each other but cannot overlap except for the given crossings. At the crossings, both snakes must go straight. The heads and tails are given, but their pairing is unknown. The number on the right indicates the number of cells occupied by one snake, and the numbers below indicate the number of cells occupied by one snake.

(Rules and example from WPC 2018 IB. Letters are only for illustrative purpose)

Loop around Snake[edit]

See Simple Loop#Loop around Snake.

Snail on Snake[edit]

See Magic Snail#Snail on Snake.

Easy as Word Snake[edit]

Easy as Word Snake Example.png Easy as Word Snake Example Solution.png

Hybrid of Easy as clues and Word Snake. First appeared on WPC 2019. Author of the puzzle was Rainer Biegler (Germany).

"Wortschlange" from Logic Masters 2011 has a similar rule as Word Snake, but outside clues indicate the numbers of vowels in the row.

Rules: Place a snake. The cells of the snake contain the sequence of letters and digits shown below (one character per cell, no spaces). Head and tail of the snake are given. The numbers outside the grid (above and to the left) indicate how many snake cells appear in the respective row or column.

(Rules and example from WPC 2019 IB)

Coral Snake[edit]

See List of Coral variants#Coral Snake.

Appearances in the past WPCs[edit]

References[edit]