Move with Arrow keys. Numbers 1-9 leave a hint in the grid, and 0 erases the current cell. H shows a hint for the current cell. Space changes display zoom. Esc pauses the game. M toggles muting. Z (or Backspace) rewind the last few steps in easier difficulties.
Push crates (one at a time) into the grid in the center of the board to form a sudoku solution. Push bomb crates into numbered crates to destroy them.