I want to give you credit for something I'm not seeing in the other comments: accessibility. I love being able to just open a game I have no idea about and get hooked right from the start.
The tutorial section was superb. silly and quick, yet completely prepared me for the entirety of the game. I think it helps that you didn't necessarily break into unexplored mechanics/concepts with this game, but all the more reason why the UI should be simple and intuitive.
I see a lot of people are suggesting some story elements to enhance the gameplay experience, and I certainly won't say NOT to do it, especially if you had something already in mind that you wanted to add in; but honestly, I'm not sure this game would benefit from it. Since stories are used to give context to the world we're in, we often see the bulk of them in the beginning of the game, along with the tutorial elements. And like I said earlier the bare bones, silly walkthrough of the training/fighting/shopping was what got me able to invest so quickly in the game. If that experience had been two minutes longer, it would have most certainly dampened my interest. But that said, the art and style and overall flavor of the game were great all around, and I'm sure I actually would enjoy more content from you in the form of a story arc. I guess my suggestion only applies to you if you just shove some half-assed nonsense in there without giving it the time and effort you gave the rest of the game (which it doesn't seem like you would do).
So yeah, great game! Would love to see more. And I will not rest until that last kid is found... (I have a sinking feeling he'll be waiting for me somewhere at the end of that damn armory)