Ben Brooks shares his frustration of app developers adding game-like features to their apps:

“If I pay for your app, why do I still need to jump through hoops to get all of the features of your app?”

He specifically calls out Clear after seeing a survey on the themes you can unlock with certain apps installed.

I agree with Ben. I like Clear as an app but I don’t like having to guess or discover by accident what themes are available to me. Although, the point of Clear is to track your to-do list. If you’re worried about themes, you’re doing it wrong.