I found myself a lot of log in problem with Unity. And I finally found the solution, thanks to stackoverflow.com , https://github.com/playgameservices/play-games-plugin-for-unity , Unity course I had attended. Here is step by step need to be done. Let's get HEADACHE 1) Create a project apk out from Unity Engine. - When you want to start create create an apps from Unity Engine, please do not import Play Games Service yet. Do it after you upload apk file to Google Play Console. - Make sure Package Name had been changed. - Create a keystore if don't have. - Build your android apps - After build, it will open a folder with a apk file. 2) Upload to Google Play Console Alpha Test. - Go to https://play.google.com/apps/publish (If you can't get in, please purchase Google developer license with Gmail Account) - Create new application - Enter title name and start create. (may need wait a while for google to create a new application for y