title: Repeat Unity game Task on android every x hours
body: <p>I'm working on a Unity game that is for Android. I don't have much experience with it, so I wanted to know the way to create mission every four hours. </p>
  
  <p>Right now I just invoke repeating the asynchronic Task to fetch the data from Firebase (it works perfectly fine), but I have doubts about this solution. I'm not sure how it works -> if the user turns off the app, will it be able to send notifications that the mission was created, or the app have to run in the background? 
  In case users quit I will store the time in static variable and compare the time when user logs in again.
  I was thinking about doing it from the back-end side - Firebase or Playfab -> sending the trigger to start the task every 4 hours, but I'm also not sure how it works -> if the user will have his app turned off, does it mean that he will miss the trigger?</p>
  
  <p>Will greatly appreciate any suggestions!</p>