Logic Masters Deutschland e.V.

Had this cheeky idea for a sequel after Cambrian, a Still Life puzzle using a ruleset based on John Conway's Game of Life (see the examples further below). This one I would say is a bit harder than Cambrian, but should have its share of rewarding moments after each tough spot.

RULES

Normal sudoku rules apply: Place the digits 1 to 9 in each row, column, and 3x3 box.

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/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)

PALINDROMES
– All lines in the grid are Palindromes, where the order of digits along a line reads the same forwards and backwards (eg, 1-4-7-4-1). The one dot is its own one digit palindrome.
– Every digit on a Palindrome Line must either be a valid CIRCLED cell or a valid SQUARED cell, or both at once, per the Still Life rules. This rule also applies to the one digit palindrome (ie, the cell with the dot).




==== 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, 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. John Conway Game of Life