Arrow keys move between squares. Enter or Space colours the square with the selected colour. Number keys 1 to 9 pick a colour. Plus and minus zoom, F fits the picture, H finds a square, Z undoes.
Laying out the squares…
Paused
squares colouring hints
Keys: arrows move, Enter or Space colours, 1–9 pick a colour, + and − zoom, F fits, H finds a square, Z undoes, Y redoes. Hold Space and drag, or use Pan, to move the picture.