If you have multiple game accounts linked to Google, you can switch between them using the Google Play Games system Android app.

1. Add the required Google account in the device settings (Settings - Accounts - Add account - Google).
2. Launch the Google Play Games app.
3. In the upper right corner, tap the button with three dots and then select "Settings".
4. In the "Your data" section of the settings, tap "Change account for games." The current account for the game will be specified here.
5. In the "Change the account by game" section, locate Zero City. The current account for the game will be specified here.
6. To change it, tap "Change" and select the desired Google Play Games account from the available options.
7. Launch the game.
8. Open the game Settings - Account - Account Management.
9. Click on the button with the Google Play Games icon on it. If a game account is associated with the previously selected Google Play Games account, you will be prompted to download it to your device.

Please note that this procedure must be done every time you want to switch between different accounts. Therefore, if you actively play on several game accounts, then the "Ask each time" option may be more convenient for you (step 6). In this case, the Google Play Games account selection window will appear automatically every time you start the game. After selecting the desired account, you will be able to download the progress associated with it through the game settings.

Alternatively, you can link your game accounts to an ID. This will allow you to switch between them directly from the in-game settings.