Core

• Engine various structures
• The Unreal Engine Game Framework: From int main() to BeginPlay
• Garbage Collection

Classes and types

Game Framework Objects

• Detailed list here (WizardCell)
• Another more detailed list here (JPL)
• More details on UObject, UClass, CDO and UBlueprint (See also UBlueprint & UBlueprintGeneratedClass)

Object

• UObject

Actors

• AActor

Blueprints

• UBlueprint & UBlueprintGeneratedClass
• Blueprint Saving

Other types

• FName and GameplayTag in depth - Baffled’s blog post on the subject

Miscs

Core delegates

• See FCoreDelegates (FCoreDelegates)

Seamless and hard travel

• Wizard Cell Persistent Data Compendium

UWorld creation flow

• link

GWorld

GWorld (that shouldn’t be used in gameplay) holds a pointer to the game editor world. When in PIE it’s the PIE world, and it switch’s back to the editor world on PIE exit. See SetPlayInEditorWorld and RestoreEditorWorld.

Source call of Beginplay

Partial root is AGameModeBase::StartPlay -> GameState::HandleBeginPlay - >GetWorldSettings()->NotifyBeginPlay() which finally sets World->SetBegunPlay(true);