I really like the city/island environment and the concept of running around helping people and solving their problems—it's really cute! Just a small heads-up: after my first delivery, I encountered a softlock. It told me to go back to the post office, but I couldn't do anything. After a quick restart, though, the story continued with the brothers.
You even included a save system! The game feels really complete, with small collectibles and everything. It instantly helped me relax.