Picrossweeper

Every tile on the board is secretly either light or dark. Some tiles carry a number, and that number counts the light tiles in the 3×3 block around it — including itself.

That single rule is the whole game. Mark tiles light or dark, use each number to pin down its neighbours, and the hidden picture comes out of the grid as you go. Every puzzle is generated so that it can be solved by pure logic — there is never anything to guess.