1H: Protium
(Published on 11. September 2026, 01:00 by RightHandedNeutrino)
This is the first of three 'simpler'
Still Life
puzzles that do not feature other rules or variants, and were inspired by
Metroid.
Consider solving
Deuterium
and
Tritium
next!
More puzzles using this ruleset were popularized by Kafkapharnaum (who test-solved this puzzle) and Sktx.
Check out the complete list of all the Still Life puzzles!
Rules:
Normal sudoku rules apply
Place the digits 1 to 9 in each row, column, and 3x3 box.
Still Life
Shade some cells green ("live 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 grey – cell ("dead 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)
Not all circled and squared cells are necessarily given.
Play the puzzle on Sudokupad
More puzzles using this ruleset were popularized by Kafkapharnaum (who test-solved this puzzle) and Sktx.
Check out the complete list of all the Still Life puzzles!
Rules:
Normal sudoku rules apply
Place the digits 1 to 9 in each row, column, and 3x3 box.
Still Life
Shade some cells green ("live 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 grey – cell ("dead 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)
Not all circled and squared cells are necessarily given.
Play the puzzle on Sudokupad
Solution code: Digits in live cells in row 5 (read left to right) followed by digits in dead cells in row 6 (read left to right)
Last changed on -
Solved by Kafkapharnaum, oiyad, wullemuus
Comments
Last changed on 11. September 2026, 04:11
on 11. September 2026, 04:10 by Kafkapharnaum
Very nicely crafted path with fun bounces, and overall a genuinely approachable 9x9 Still Life puzzle considering the learning curve of this ruleset. Definitely spikes up in difficulty towards the last third or so of the shading part however, imo, so new solvers beware!
And bold move publishing the full trio all at once – let’s hope at least a handful of brave solvers will not let themselves be intimidated by this pile of circles and squares and be hooked such as to then go try the other two puzzles (Which I still have to do myself, actually!)
