When a line is cleared (which may contain multiple colors), any contiguous region of squares that is adjacent to a removed square in that line and shares its color is also removed.
Diagonals are included when considering adjacency — both in defining contiguous regions and in determining adjacency to a removed square of the same color in the cleared line.
When a line is removed, any squares above it shift down.
The distance a square shifts down equals the number of squares below it in its column that have been removed. This number may exceed the number of lines cleared due to the additional removal of contiguous regions as described above.
Is this a novel variant?
Do you think it would be fun to play?