Unreal Engine - Game Flow Chart

StartEngine(Editor)-> (UEditorEngine) Init->  (UEngine) Start-> Uses presses "Play In Editor" button

-> Create UGameInstance-> (UGameInstancce) InitializePIE-> (UGameInstance) Init

-> Create UOnlineSession and register delegates-> (UEditorEngine) CreatePIEGameInstance

->(UEditorEngine) StartPIEGameInstance-> (UWorld) BeginPlay

StartEngine(standalone)-> (UGameEngine)Init-> Create UGameInstance

->(UGameInstance)InititalizeStandalone-> (UGameInstance)Init

-> Create UOnlineSession and register delegates-> (UEngine)Start -> (UWorld) BeginPlay

(UWorld) BeginPlay-> (AGameMode)StartPlay-> (AGameMode)StartMatch

-> Spawn Actors and begin the game