I seen a post in
Patch notes 2013-11-19
Mobile
• Various bugs were resolved.
• You can now also reduce the time for missions, trainings and so on by watching a short video on the mobile client. Additionally, the offerwall is now also available for mobile users.
there is 'offerwall' written there,
i recieved message to in game, that we can get free donuts from offerwall?
what is offerwall really?
thanks for the answer.