Too Long; Didn't Read
User retention happens via activation and <a href="https://hackernoon.com/tagged/onboarding" target="_blank">onboarding</a>, not notification spam or <a href="https://hackernoon.com/tagged/addition" target="_blank">addition</a> of new features that eventually leads to feature fatigue. How do you introduce your product to a new user for the first time? You use onboarding. Fairly self-explanatory, really.