The visual style is really great! The game reminds me a bit of OSU. It get a bit repetitive but it's relaxing and a fun challenge. The music is nice and relaxing, so it all makes for an interesting experience.
I like the idea of lowering the water in order to know what's behind, but it was taking a little to long for me and had to stop. This is the main thing that I would change. One way of course would be to lower the amount of orbs needed to clear it. Another way which would fit the game really well imo, is letting the player stop clicking orbs and enjoying the music without losing their progress. This way you can stop whenever you want if you're tired and need a break, but you know that you won't have to start over again. You could stop and just listen to the music, maybe the water keeps going down but slower, then you play a little bit again, so on and forth. That would really make for a relaxing experience because you don't feel pressured to constantly keep pressing the orbs. It got a little tiring for me, especially when I didn't see the water move that much.