ECHO

Every move comes back. Drag a ball and it slides one square — then, every three turns, every ball you have moved repeats its move. Forever. Balls smash gems of their own colour, so you are never just solving a puzzle: you are building a machine out of your own past, and then watching it work. Line several balls up to strike on the same beat and the whole board goes off at once. 160 levels, every one of them verified solvable before it shipped, plus a Daily Echo that changes at midnight.