After playing the game and reading the description, I understand that the game is trying to explore loneliness and desperation to end the game by eating the red cube.
The concept of having background music as the sound of the waves at the sea sort of actually made the mood more calming and relaxing (to me). I was actually playing the game feeling quite relaxed and even after eating the red cube and watching the man sinking into the ocean, I didn’t really feel the part of horror in the game.
Personally, I feel that loneliness comes from the feeling when you are present but everyone treats you as if you were absent or invisible to them. I personally (to me) feel that the concept of feeling lonely is a lacking in the game because we are just playing as an old man fishing until we want them to stop by consuming the red cube. I hope that you can develop and build on the idea of loneliness.
Overall, this is a very interesting and good game that will attract many people’s attention. I hope to see more endings and a better version of the game in the future. Good job!