What Is SSO (Single Sign-On)? A Game Developer's Guide

Single Sign-On (SSO) means a player uses one identity they already own — their Google, Apple, or Steam account — to sign in to your game, instead of creating a brand-new username and password just for you.

For a player, it's the "Sign in with Google" button. One tap, no new password, and they're in. For you as the developer, it means you're not the one storing passwords or building a "forgot my password" flow.

Why "single" sign-on

The name comes from the original idea: sign in once to an identity provider, and reuse that session across many separate services without logging in again. A player who's already signed into Google on their phone can authenticate to your game without typing anything.

In game development, SSO almost always shows up as social login. The identity provider is a platform the player already trusts — Google, Apple, Steam, Discord — and your game is the service they're signing in to.

What SSO actually does for a game

A few concrete things change when you use SSO instead of your own email/password system:

• No passwords to store. You never hold the player's credentials, so you're not the target when passwords leak. The identity provider handles authentication.
• Less sign-up friction. Every extra field on a sign-up form drops completion. A single tap keeps more players in the funnel.
• Cross-device continuity. Because the identity lives with the provider, a player who reinstalls or switches devices signs back into the same account.
• A trusted name on the button. Players are more willing to tap "Sign in with Google" than to hand a new indie game a fresh password.

The trade-off is that you now depend on an external provider's login flow — and each one has its own quirks. Apple's sign-in is mandatory on iOS if you offer any other social login. Steam authenticates through OpenID and won't give you an email address at all. Those differences are real, and they're where most of the integration work hides.

SSO vs. OAuth vs. authentication

These terms get used interchangeably, but they're different layers:

• Authentication is the general question: is this player who they claim to be?
• SSO is a strategy for answering it — reuse one identity across services.
• OAuth 2.0 is a protocol that implements it. It's the actual request/response dance behind "Sign in with Google."

So a player tapping "Sign in with Google" is authenticating (proving identity), via SSO (reusing their Google account), using OAuth 2.0 (the underlying protocol).

SSO in Unity, without the plumbing

Wiring OAuth yourself means handling redirect URIs, token exchanges, a client secret you can't ship in the build, and deep links back into the game — per provider. That's a lot of moving parts for a login button.

Oathwall handles that layer. Your game calls one method with a provider name, the OAuth exchange runs on Oathwall's servers, and you get the finished result back. If you want to see it end to end, the Google Sign-In in Unity guide walks through a real setup, the Unity authentication guide maps out every provider and concept, and the docs cover the dashboard fields. Curious about the protocol under the button? OAuth 2.0 explained breaks it down.

Oathwall is available on the Unity Asset Store.