List of Coral variants

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There are a lot of Coral variants. Refer to Coral for the standard definition of the word "coral" in here.

First Seen Coral[edit]

First Seen Coral Example.png First Seen Coral Example Solution.png

First appeared on Moscow Cup 2009. The puzzle was written by Andrey Bogdanov (Russia).

Shade some cells to make standard Coral. The clues outside the grids represent the length of the first filled cell block in that direction.

(Rules (modified) and example from WPC 2011 IB)

Coral Snake[edit]

Coral Snake Example.png Coral Snake Example Solution.png

Hybrid with Snake. Invented by Rainer Biegler (Germany). First appeared on LMD portal in 2012.

Shade some cells to create a standard Coral and a standard Snake. Cells marked with circles contain head and tail of the snake. Snake and coral cannot overlap, and coral cells and snake cells cannot share an edge, but they can touch diagonally.

The clues outside the grid describe the contents of the respective row or column. For each row or column, one of the numbers indicates the number of snake cells in the respective row or column; each other number corresponds to a contiguous group of coral cells, the number indicates the length of that group. However, if a row or column contains no coral cells or no snake cells at all, the clue number 0 will be omitted.

(Rules (modified) and example from WPC 2019 IB)

Coral + Star Battle[edit]

Hybrid with Gaps rather than Star Battle. First appeared on LMD portal in 2015. Invented by Christian Halberstadt (Germany).

Shade some cells so that all shaded cells are connected, all unshaded cells are connected to the border of the grid and no 2×2 square is completely shaded.

Further, place stars into some unshaded cells, so that there are exactly two stars in each row and column. The stars do not touch each other, not even diagonally.

The clues outside the grid describe the contents of the respective row or column. For each row or column, one of the numbers indicates the number of cells between the two stars; each other number corresponds to a contiguous group of shaded cells, the number indicates the length of that group. Some numbers have been replaced by question marks. For each row and column, the clue numbers are sorted in increasing order, with the question marks always at the beginning, regardless of which numbers they replace. For some rows or columns the clues have been omitted entirely.

(Rules from WPC 2019 IB)

Sky Coral[edit]

Sky Coral Example.png Sky Coral Example Solution.png

Hybrid with Skyscrapers clues. First appeared on WPC 2018/Round 3. The puzzle was written by Jiří Hrdina (Czech Rep.).

Shade some cells to make standard Coral. The numbers at the borders indicate how many blocks are visible if the lengths of the blocks were their heights.

(Example from WPC 2018 IB)

With Vertex Hints[edit]

Coral With Vertex Hints Example.png Coral With Vertex Hints Example Solution.png

Addition of (inverted) Creek clues. First appeared on WPC 2018/Round 5. The puzzle was written by Jiří Hrdina.

Shade some cells to make standard Coral. The numbers on the vertices indicate the number of painted cells touching the given vertex.

(Example from WPC 2018 IB)

Inner Coral[edit]

Inner Coral Example.png Inner Coral Example Solution.png

First appeared on WPC 2018/Round 5. The puzzle was written by Jiří Hrdina.

Shade some cells to make standard Coral. Clues denote all of the lengths of the first Coral segments visible from this cell in the four directions (vertically and horizontally) in no particular order.

(Example from WPC 2018 IB)

Double Coral[edit]

Double Coral Example.png Double Coral Example Solution.png

First appeared on WPC 2018/Round 10, "Double Trouble". The puzzle was written by Jiří Hrdina.

Place two corals in the grid. Use X and O to mark the fields occupied by the two corals.

The numbers on the edge indicate the lengths of successive blocks of coral cells, but not necessarily in the correct order. There must be at least one other cell between two blocks. All the cells must be filled by at least one of the corals. All the cells where the corals overlap are marked. Hints on the right belong to one of the corals, hints below belong to the other one.

(Rules and Example from WPC 2018 IB)

Regional Coral Example.png Regional Coral Example Solution.png

Regional Coral[edit]

First appeared on WPC 2018/Round 11, "Regional". The puzzle was written by Jiří Hrdina.

Additional rule: In each region, the exactly same number of cells are shaded. Solvers must determine the number of shaded cells.

(Example from WPC 2018 IB)

Coral with Letters[edit]

Coral with Letters Example.png Coral with Letters Example Solution.png

First appeared on WPC 2018/Round 12, "Innovatives". Invented by Jiří Hrdina.

Rules: Shaded cells form a standard coral. Furthermore, place a given set of letters in the painted cells so that each letter appears exactly once in each row and column. The hints around the grid show all the letters that can be found on the first coral segment from the given side, in correct order (from top to bottom resp. from left to right). Dash means there is no letter on the first segment.

(Rules and example (A, B) from WPC 2018 IB)

Appearances in the past WPCs[edit]