Really cute game! Love how the art style is in a child-like manner, really emphasizes the innocent nature of the game! I love how the mechanics flow well with wind currents making the letter fly and the various obstacles that get in your way like the birds and the water! Controlling other characters was also very unique and I didn't expect that I would be able to do that! Also loved the ending :)
My only feedback is to make the respawn points more forgiving. I kept getting eaten by birds and had to restart from a far away checkpoint, which did get somewhat frustrating. Overall, great job!