You're definitely on the right track. The sound design is the strongest aspect, which did the most to sell the mood. I also appreciate the color palette choice: majority dark and gray, with a splash of hazy warmth.
I do notice you had 30 minutes to spare. What if some % of the messages were negative, and clicking on them played a more sour effect? Games do thrive on conflict, and thinking terms of "loss condition" / "win condition" will be the next step in your journey.
You might feel that this suggestion would tarnish the purity of your design; it might be a core value of yours that the game should be 100% friendly, positive, and unharmful. My only other suggestion, then, would be to do some vis dev exploring images that convey this mood you wish to convey. Pinterest's algorithm is excellent: once you find a single image whose aesthetic you like, it will give you dozens if not hundreds of similar images. Use this to explore your taste and challenge yourself to determine what, specifically, you like about each image. That alone is enough. The style and taste will begin to permeate through your work subconsciously.
Keep it up and I look forward to seeing your next project!