This level is all about making big squares.
Remember that any time you complete an enclosed shape larger than a 2×2 square, it counts as a square. If you enclose dots that aren’t part of the outline of the shape, they turn into bombs. I found myself making at least one L-shaped shape (joining 3 3×3 squares) because there was at least one dot for each 3×3 square that was a different color.
Make sure to remember that the dots in columns with open spaces fall at twice the rate of the columns with only dots.
It helps to restart until you have at least one 3×3 square that you can complete within the first two moves, just because it temporarily reduces the number of colors surrounding the open spaces that you’ll have to match up to make the next square.