Black Survival can be accessed with Google account or Apple ID.
You can have the same experience regardless of your devices.
To move your current account to other device, check your device's operating system and follow the procedures listed.

Android > Android
On the device you would like to transfer your account to, go to 'Settings -- Account - Add Account' and add Google account you have been using
Popup will appear with list of accounts added to your device.
Choose the account you want to sign in with on the list.

iOS > iOS
Go to Game Center in Settings menu on the device you want to transfer to
And sign in with Apple ID you are using and start Black Survival.

iOS > to another platform
1. Start the game on iOS, and go to 'Main Lobby - Settings - Device Sync - Send to Android', and remember the code shown.
2. Start the game on Android device you want to transfer to and sign in with new Google account
Go to 'Main Lobby - Settings - Device Sync - Bring from iOS'. Enter the code you got from iOS and account transfer will be complete.
*Caution - After the transfer is complete, you can't play the game with same account on iOS Or sign in with Google account before the device sync.

Android > to another platform
1. Start the game on Android, and go to 'Main Lobby - Settings - Device sync - Send to iOS', and remember the code shown
2. Start the game on iOS device you want to transfer to and sign in with Apple ID
Go to 'Main Lobby - Settings - Device sync - Bring from Android'. Enter the code you got from Android and account transfer will be complete.
*Caution - After the transfer is complete, you can't play the game with same account on Android Or sign in with Apple ID before the device sync.

Steam > to another platform
1. After accessing from Steam, click the 'Lobby - Settings - Device Sync' button.
(Please remember the code.)
2. Click 'Lobby - Settings - Add Account' in the app or program you want to move to.
Enter the code you received from Steam to complete the account transfer.
*Warning - existing account will be deleted when it is overwritten.