Fossil Mosaic

Every control works with touch or click. Use Tab, then Enter or Space. Movement: arrows or WASD. R resets; Z undoes. Sudoku: choose row, cell, then digit (number keys also work). A full-grid overview is shown above the editable row. No download or account required.

Calm puzzles permit unlimited undo and reset. Hazard, resource, and timed studies retain defeat. Terminal boards accept only undo or reset.