Quick Start

This guide will get you from zero to a working multiplayer lobby in minutes using Device ID authentication - the simplest way to test EOS features.

Device ID creates an anonymous account tied to the device. Perfect for testing.

Use the Login Using Connect Interface node with Device ID as the login method.

Device ID Login

Display Name cannot be empty.

// Build.cs
PrivateDependencyModuleNames.AddRange(new string[] { "OnlineSubsystem", "OnlineSubsystemUtils" });

// Header
#include "OnlineSubsystem.h"
#include "OnlineSubsystemUtils.h"
#include "Interfaces/OnlineIdentityInterface.h"

void LoginWithDeviceID();
void OnLoginComplete(int32 LocalUserNum, bool bWasSuccess, const FUniqueNetId& UserId, const FString& Error);

// Source
void UMyClass::LoginWithDeviceID()
{
    if (const IOnlineSubsystem* OnlineSub = Online::GetSubsystem(GetWorld()))
    {
        if (const IOnlineIdentityPtr Identity = OnlineSub->GetIdentityInterface())
        {
            FOnlineAccountCredentials Credentials;
            Credentials.Type = "noeas_+_EIK_ECT_DEVICEID_ACCESS_TOKEN";
            Credentials.Id = "PlayerName"; // Display name

            Identity->OnLoginCompleteDelegates->AddUObject(this, &UMyClass::OnLoginComplete);
            Identity->Login(0, Credentials);
        }
    }
}

void UMyClass::OnLoginComplete(int32 LocalUserNum, bool bWasSuccess, const FUniqueNetId& UserId, const FString& Error)
{
    if (bWasSuccess)
    {
        UE_LOG(LogTemp, Log, TEXT("Login successful! UserID: %s"), *UserId.ToString());
    }
    else
    {
        UE_LOG(LogTemp, Error, TEXT("Login failed: %s"), *Error);
    }
}

2. Create a Lobby

Once logged in, create a lobby that others can join.

Use the Create EIK Lobby node after successful login.

Key settings:

Max Players: How many players can join
Is Public: Whether the lobby appears in search results
Use Voice Chat: Enable built-in voice communication

void UMyClass::CreateLobby()
{
    if (const IOnlineSubsystem* OnlineSub = Online::GetSubsystem(GetWorld()))
    {
        if (const IOnlineLobbyPtr Lobby = OnlineSub->GetLobbyInterface())
        {
            FOnlineSessionSettings Settings;
            Settings.NumPublicConnections = 4;
            Settings.bShouldAdvertise = true;
            Settings.bUsesPresence = true;

            Lobby->OnCreateLobbyCompleteDelegates.AddUObject(this, &UMyClass::OnLobbyCreated);
            Lobby->CreateLobby(*Online::GetSubsystem(GetWorld())->GetIdentityInterface()->GetUniquePlayerId(0), Settings);
        }
    }
}

3. Find and Join Lobbies

Search for available lobbies and join one.

Use Find EIK Lobbies to search for available lobbies
The results contain a list of lobbies with their details
Use Join EIK Lobby with the selected lobby to connect

void UMyClass::FindLobbies()
{
    if (const IOnlineSubsystem* OnlineSub = Online::GetSubsystem(GetWorld()))
    {
        if (const IOnlineLobbyPtr Lobby = OnlineSub->GetLobbyInterface())
        {
            Lobby->OnFindLobbiesCompleteDelegates.AddUObject(this, &UMyClass::OnLobbiesFound);
            Lobby->FindLobbies(*Online::GetSubsystem(GetWorld())->GetIdentityInterface()->GetUniquePlayerId(0), FOnlineLobbySearchQuery());
        }
    }
}

Testing Locally

To test multiplayer on a single machine:

Launch two instances of your game (use standalone game, not PIE for the second instance)
Login on both with different display names
Create a lobby on one instance
Find and join from the other instance

EIK supports Play-In-Editor (PIE) testing with multiple clients. Go to Play → Advanced Settings and set the number of players.

Next Steps

Authentication Methods - Learn about Epic Games, Steam, and other login options
Lobbies - Advanced lobby features
Sessions - For dedicated server setups
Voice Chat - Add voice communication

Quick Start

1. Login with Device ID

2. Create a Lobby

3. Find and Join Lobbies

Testing Locally

Next Steps

On this page