Reward For App Review In Play Store?

Hey guys/gals. I was wondering if there are any rules against unlocking content only after someone rates your app in the Google Play store? Let’s say that I had a text messaging app that came with emojis. To unlock the full set of emojis they needed to rate the app in the Google Play store. From what I understand, you can’t tell if they actually accomplished this task, but you can create an intent that sends them to the store. After they do that, then they would have access to all the emojis. Anyone know if this is allowed or if it’s against TOS?

Never mind, i found my answer. You can’t do it.

https://play.google.com/about/storelisting-promotional/ratings-reviews-installs/

Yes, you can’t do it. Try to put the dialog to review in a good site but without rewards.

Actually I’m doing this for my apps and so far didn’t had troubles. The main factor here is to just ask for a review, not for a particular star rating(5 stars only for example). Also writing a small *info text like “you’re free to rate with how many stars you want” might help as well.