I know this is going to be an opinion that a lot of people disagree with, but hear me out:
If you're going to "game-ify" your service... make it optional.
I'm not talking "you can just ignore it" optional. I'm not talking "just don't take it seriously" optional.
No. Let me disable it.
I want to use DuoLingo and NOT know what my ranking is or who my stuff is being compared to or what my score is? Let me.
I want to disable achievements on my Xbox or Steam? Let me.
It's not that hard.
1/2