I really like the simplistic art style and the chill vibes. I do feel that the game is a little bit too focused on the random component. Perhaps an indicator or border that flashes around a block to say that it will expand? It would make it feel a little bit less random. Also, maybe having a loose condition or further incentives for progressing (though, perhaps I didn't encounter them as the game was a little bit too difficult for me). My last comment is that perhaps instead of having a 90 degree turn, having the arrow keys rotate the block slightly for better precision placement?
However, as it is, this game is really fun and incredibly chill too play. Excellent job!