From WPC unofficial wiki


Blacken some cells in the grid such that each row and each column contains exactly two blackened cells. The numbers to the left of (or above) the grid indicate the number of unblackened cells between the cells in that row (or column). Blackened cells may not touch each other, not even diagonally.

(Rules and example from PGP IB)

History of the puzzle[edit]

Invented by Erich Friedman (USA) in 2010. His first set of puzzles can be seen in his website. It may have been independently invented elsewhere considering its simple rules.


Coral + Star Battle[edit]

See Coral#Coral + Star Battle.

Gaps between Battleships[edit]

See Battleships#Gaps between Battleships.

Appearances in the past WPCs[edit]