I want to use the rest time to develop an app, which kind of app is more fun to develop?

  ios, question

For example, it will be put on gitHub, updated from time to time and maintained for a long time.

I think it’s interesting to make a personal chat app by myself. Returning to the original, it can take the kind that can be checked only by decryption, and it tastes like The Letter With Feathers. I’m going to do it.