Hay Day is a freemium mobile farming game developed and published by Supercell. Hay Day was released for iOS on 21 June 2012 and Android on 20 November 2013. According to a 2013 report, Supercell earned $30 million a month from Hay Day and Clash of Clans.
To find your player tag, open the profile menu at the top left. Then copy. Example: #GPL9QULG2. Make sure your account is linked to Supercell ID.