Welcome to the first installment of our series, where we’ll guide you through adding social login functionality to your Unity game on Android. We’ll demonstrate how to build a simple Android application in Unity and integrate login using Google accounts, as well as manage users in Firebase. I will share with you the good, the bad and the ugly part of what I’ve learned during the process.

Background

In an Unity Android game project I was working on, I needed to provide players with a way to log in using their Google accounts. The game’s backend API was on Google Cloud and only allows authorized calls using the player’s identity. I required a method to seamlessly integrate login functionality directly within the game, eliminating the need for users to register on external websites.

There were several options to enable third-party social login, including the following providers:

• Auth0
• AWS Cognito
• Firebase
• Unity Authentication
• Google Sign-In Unity Plugin

Unity Authentication

Unity’s own authentication gaming service seems like a good fit and supports a wide range of authentication providers and it integrates seamlessly with Unity.

• Google Play Games
• Unity Player Accounts
• Google
• Apple
• Facebook
• Steam
• OpenID
• Custom ID

To authenticate using Google Account you would have to use the Google Play Games plugin and only support v0.10.14 or earlier of the plugin. After spending hours attempting to make this work in Unity with version v0.10.14, I successfully signed in with my Google Account. However, obtaining the ID token from Google proved to be a challenge.

Additionally, I encountered issues due to outdated documentation for v0.10.14, where several methods were no longer supported. Ultimately, I opted for a less convoluted approach.

Google Sign-In Unity Plugin

Another solution was the Google Sign-In Unity Plugin. This plugin supports authentication with Google Accounts through OAuth and is compatible with both Android and iOS. However, please note that this plugin is quite old—almost 6 years old as of this writing. When I attempted to import this plugin into my Unity project, which is running version 2022, I discovered that it is no longer supported.

AWS Cognito

The AWS Cognito service offers third-party integration with Google Accounts see here. While it also supports Unity, the challenge lies in the similarity to the Unity Authentication approach. Specifically, I would need to utilize the Google Play Games plugin version 0.10.14, which is both convoluted and outdated.

Auth0

Auth0 is a popular SaaS provider that offers a wide range of support for OAuth authentication. However, the challenge lies in the lack of readily available resources and documentation for integrating it with Unity. To achieve this integration, you would need to write a significant amount of custom code.

Firebase

Firebase has an Authentication service that closely resembles AWS Cognito User Pool and allows seamless third-party integration with Google Account. The Firebase SDK also supports Unity. The challenge with Firebase is that you would still need to use a way to integrate OAuth2 into your Unity game through custom code or library.

Final approach

After dedicating countless hours and days to researching and implementing various providers, I’ve ultimately discovered a solution that perfectly aligns with my requirements. I’ve decided to go with Firebase using their Unity plugin and combine it with another Unity library called i5 Toolkit that supports OpenID connect provider. Youtubes like Authenticate users using google in Unity and Firebase with OAuth2.0 and reading the documentation has helped me a lot in implementing it myself.

Step-by-step guide

I will guide you through implementing social login for a Unity Android game, allowing users to log in using their Google accounts. We will demonstrate how to integrate Firebase SDK and i5 Toolkit to facilitate the authentication process flow and retrieve the JWT token that can be used to authorize calls to Google cloud API Gateway.

To follow this guide you will need to have the following:

• Unity version 2022
• Visual Studio Code
• Android phone (I’ve tested on Galaxy Z Fold, but any model should be fine)

What we will cover in Part 1

In this part of the series we will be covering the following steps:

• Unity setup
  • Install Android Build Support module
  • Create new project
• Setup Project structure in Unity
• Create sign in UI in Unity
• Setup Android Build
  • Create keystore for signing
  • Set Android API Level

Unity setup

If you haven’t already, download and install Unity. Make sure to install version 2022.

Install Android Build Support module

To enable Android builds, you’ll need to install the Android Build Support module. Navigate to the Installs menu in your Unity Hub, and click on the gear icon next to your Unity version and choose , as depicted in figure 2.

This will open a new window. Put a check mark on the Android Build Support ensure that both OpenJDK and Android SDK & NDK Tools are checked and click Install button, see figure 3. In my case I’ve already installed the tools so the checkbox are grayed out.

Create new project

Next, create a new project named SocialLogin and select the 3D Core template.

A new Unity Editor will start and load your project, see figure 5.

Setup Project structure in Unity

Now that we’ve set up a new Unity project, let’s organize it. We’ll create a fresh folder called Projects to keep all our custom assets and C# code. Certainly! Here’s an improved version of the instructions:

1. Right-click on the Assets folder in your Unity project window.
2. Select Create ➡️ Folder.
3. Name the new folder Projects.
4. Create another folder named Scripts.
5. Drag and drop the existing Scenes and the new Scripts folder into the newly created Projects folder.

Now that we’ve established the fundamental project structure, our next step is to create a user interface for signing in to a Google account.

Create sign in UI in Unity

In this step we will be creating a user interface for signing in to a Google account.

1. Right-click on the SampleScene in the Hierarchy window.
2. Choose UI ➡️ Canvas.

As shown in figure 7, you now have two additional game objects added to the scene: Canvas and EventSystem.

Next, let’s create a sign-in button

1. Right-click on the Canvas object and choose UI ➡️ Button - TextMeshPro.
2. A new popup window will appear; click on Import TMP Essentials.
3. A new Button object is added to the Canvas
4. Assets for the TextMeshPro is added to your Assets folder.

Next, let’s configure the Canvas. We want the UI to scale according to the screen size, so if the screen is smaller, the UI should scale proportionally. We also want to set the width and height of the sign in button to something larger.

1. Click on the Canvas object, and in the inspector window, select UI Scale Mode ➡️ Scale With Screen Size.
2. Click on the Button object, and in the inspector window choose the Rect Transform component and set the Width ➡️ 320 and Height ➡️ 60.
3. Click on the Button ➡️ Text object, and in the inspector window choose the TextMeshPro - Text (UI) component and set the Text Input ➡️ Sign In.

Now if you select the Game tab in your 3D Scene window you should see a grey button with the text Sign In, see figure 10.

Setup Android Build

In this step, we will configure Unity to build our scene for an Android app.

1. Choose File ➡️ Build Settings… from the menu
2. Then click on the Android platform and click on the Swtich Platform button.

Now your project is ready to be built for Android.

Create keystore for signing

Android requires that all apps be digitally signed with a certificate before they can be installed. So let’s configure Unity to create a keystore for signing our Android game.

1. Choose File ➡️ Build Settings… from the menu
2. Click on the Player Settings…
3. Expand the Publishing Settings
4. Click on Keystore Manager… button
5. Enter a password for the keystore
6. Give the key an alias
7. Enter password for the key
8. Click the Add key button

A new keystore will be created in the location specified. The keystore necessitates that our game be built with native 64-bit binary support. Consequently, we must configure the following settings.:

1. Still in Player settings expand the Other settings
2. Set Configuration ➡️ Scripting Backend ➡️ IL2CPP
3. Put a checkmark on Configuration ➡️ Target Architectures ➡️ ARM64

Set Android API Level

We will be importing packages that require a minimum Android API level of 23 and a target level of 34. This requires configuring the following:

1. In Player settings expand the Other settings
2. Set Identification ➡️ Minimum API Level ➡️ API Level 23
3. Set Identification ➡️ Target API Level ➡️ API Level 34

Conclusion

In this part of our series, we’ve covered how to configure Unity for building our Android game. Additionally, we’ve created a user interface (UI) that allows players to sign in using their Google accounts.

This concludes part 1 of our series. In part2, I’ll guide you through creating a Google OAuth Client ID that our game can use for enabling sign-in with Google Accounts.