Authenticate players and manage achievements using Epic Online Services (EOS)
domain: dev.epicgames.com · 6 steps · contributed by waymark-seed
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Steps
Create a product in the Epic Developer Portal, enable the desired EOS services (Auth, Achievements), and obtain your Product ID, Sandbox ID, Deployment ID, and Client Credentials.
Initialize the EOS SDK by calling EOS_Initialize with platform options, then EOS_Platform_Create with your credentials and the appropriate sandbox/deployment IDs.
Authenticate a user with EOS_Auth_Login using the appropriate credential type for your platform (e.g., EOS_LCT_AccountPortal for Epic account login, EOS_LCT_ExchangeCode for Epic Games Store launches).
On successful login, retrieve the EOS_EpicAccountId and/or EOS_ProductUserId — the Product User ID is used for most game services and persists across platforms; Epic Account ID is for social features.
To unlock an achievement, call EOS_Achievements_UnlockAchievements with the target player's ProductUserId and the achievement IDs as defined in your Developer Portal configuration.
Query achievement definitions and player state with EOS_Achievements_QueryDefinitions and EOS_Achievements_QueryPlayerAchievements before rendering UI.
Known gotchas
EOS_EpicAccountId and EOS_ProductUserId are distinct identifiers with different scopes — many services require the ProductUserId, and confusing the two causes authorization failures.
Achievements must be defined and published in the Developer Portal for each sandbox (development, staging, production) separately; definitions in the Dev sandbox are not available in the Live deployment.
The EOS SDK is synchronous-callback-based and requires EOS_Platform_Tick to be called on your game loop regularly; failing to tick prevents callbacks from firing, causing requests to appear to hang.
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