Logic Masters Deutschland e.V.

Those of you who follow the front pages might have noticed a number of new Still Life puzzles lately, by RightHandedNeutrino, and unapologetically on the harder side too. This has both prompted me to not only revisit the ruleset, but to also deviate from my previous efforts to create the most approachable Still Life sudoku that I could, and which led to this dynamic Fog of War puzzle. In other words, this one here is a challenge! Big thanks to the above mentioned RightHandedNeutrino for testing it.

The Still Life variant is infamous for its high learning curve, but if you want to cautiously dip your toes, you can try the two and three star ones of this complete list of all the Still Life puzzles. Plus, as always, Sktx's examples highlighting many of the common pitfalls are presented further below.



RULES

Normal sudoku rules apply
• Each of the digits 1 to 9 must appear once in every row, column and 3x3 box.
• The color indications below are but suggestions and do not affect anything.

STILL LIFE
• Shade some cells green ("active cells") such that the – up to – eight cells neighboring each green cell contain exactly 2 or 3 other green cells and the neighbors of each 'unshaded' – or black/red/blue/etc. – cell ("inactive cells") do not contain exactly 3 green cells.
— A CIRCLED cell's digit indicates the number of cells that are in the SAME state as its own in its neighborhood, including its own cell.
— A SQUARED cell's digit indicates the number of cells that are in a DIFFERENT state from its own in its neighborhood (therefore not including its own cell).

DOUBLE ARROWS
• The sum of the digits along each line connecting two oversized circles (summing circles) is equal to the sum of the digits in these circles.
• The small circles and squares along the Double Arrow lines are Still Life clues acting in the same capacity as the larger, non connected ones.
• The summing circles of the Double Arrows act by default as CIRCLED Still Life clues.


==== EXAMPLES ====

In Example 1, a 3x3 box with a Game of Life pattern is shown (green for active cells, grey for inactive cells). But the cells marked with a ! are unstable : they either are inactive but with 3 active neighbors, or active but with less than 2 or more than 3 active neighbors. Therefore this pattern is not a Still Life pattern, and can not appear in a Still Life Sudoku puzzle.

In Example 2 (using the digits of a normal 9x9 sudoku grid), a 3x3 box is shown filled with digits and clues (circles and squares), the Game of Life pattern that is shown is stable, and all the clues are fulfilled. This could appear in a Still Life Sudoku puzzle.