Here's an offshoot of gin rummey or poker.......a game of finding straights.
Here the playing board:
Here are the rules:
Rows and columns are divided into compartments of white squares.
Black squares create separate compartments in rows and columns.
Use single numbers (1-6) to complete a straight for each compartment
A straight is a set of numbers with no gaps and in any order
No single number can repeat in any row or column
Clues in black cells remove that number as an option in that row and column, and are not part of any straight
Here's the Coordinate Converter
Consider a black box to be zero for the conversion
Here are the cache coordinates: N39 19. C4 A6 (D1+3) W84 18 A4 F3 C1