I don't really understand how the game works. Maybe it's like Tetris but harder to perceive which mean it's hard to make it more logical.
The change in colors seems to be abrupted and kinda make it hard to control the outcome.
If we're talking about making games about "Sand", then this would get full score for the theme since it's captivated the feeling of sand rather well.
Artstyle, sound, music are all good. Mechanic is something I'd be on the sideline as I mentioned above.