Hello Tianhao Wang!
You have made a beautiful game.
You are well done.
What the game was developed on: Unity, GameMaker Studio 2, Construct 3, or on some other engine?
P.S. I develop games for Construct 3.
Not perfect yet, but I'm trying to improve my experience.
As for your game: you can add a collection of different items so that later these items can be combined and forged new weapons, I think this is a good idea :)