Your letter can change the mind of someone and make them improve for the better. Your letter is a beacon of support that will land on the desktop of whoever needs it. You are a writer who only wishes for a stranger to be happier, you only want the world to be a better place. No one knows who you are, yet you still want them to smile. Your letter, is a piece of you and your caring self, so make sure it reaches those who want to hear it.
Remember words are not just texts on a screen, they are symbolic of support and love, they can make a person smile and realize the good in the world. Your letters can help people realize that there are people out there that really do care about them. The fact that a game like this exists at all is evidence enough.
Write a letter to someone, make sure they know they aren't alone, make sure they know they are lovable and deserve to be happy. Sometimes, all we need are some kind words from a stranger.