Support charity, get puzzles!
Patron Puzzles for Philanthropy

March Mutant 19: Cross the Streams / Tetra Firma (arbitrarily inverted)

Shade in tetrominoes such that the black cells are all connected to each other through their edges, and no 2x2 cell area within the grid contains all black cells. No two congruent tetrominoes may share an edge, even if they are rotated or reflected versions of each other. In a normal Cross the Streams, numbers to the left of a row or above a column represent the groups of consecutive black cells which are in that row or column. For example, a clue of "3" means the row or column has three consecutive black cells, and a clue of "3 1" means that the row or column has a group of three consecutive black cells followed by a single black cell, separated by at least one white cell. A question mark (?) represents a group of consecutive black cells whose size is unknown; an asterisk (*) represents any number of unknown groups of black cells, including none at all. However, in this puzzle, some of the clues are inverted, and refer to the groups of white cells in that row or column. (A clue may coincidentally function as both a normal clue and an inverted one simultaneously.)

When will the arbitrary madness end???
ERRATUM: The original version of this puzzle had no clue in column 5, and more than one solution. Happy Quantity-Not-Quality Month!

3 comments

Jonah said...

Is there also the usual Tetra Firma restriction that no congruent tetrominoes share an edge?

Jonah said...

Answered my own question: yup.

prasannaseshadri said...

Seems to be a day for errors, today's CTC puzzle got canceled too. Anyway, some wonderful logic here with a nice ending, good enough to get me to solve the entire thing again after the added clue. Thanks :)

Blog Archive