GetSubsystem — get a subsystem instance (GameInstance, World, etc.)

Pure node. For GameInstance subsystems: GetGameInstance → GetSubsystem. For World subsystems: GetWorld → GetSubsystem. Subsystems are auto-instanced singletons — great for organizing game systems.

GetEnhancedInputLocalPlayerSubsystem — get Enhanced Input subsystem

Game subsystem: persistent game manager with auto-init

SETUP: Create Blueprint inheriting UGameInstanceSubsystem (or UWorldSubsystem for level-scoped). Override Initialize(Collection) to set up. Override Deinitialize to clean up. Add game variables here (Score, PlayTime, Settings). ACCESS FROM ANYWHERE: GetGameInstance → GetSubsystem(BP_GameSubsystem) → CastTo<BP_GameSubsystem> → access variables. WHY: Subsystems auto-create, auto-destroy, and don't need FindActor. Better than GameInstance for well-organized systems. UGameInstanceSubsystem persists across levels. UWorldSubsystem is recreated each level.

AddMappingContext — add input mapping context to Enhanced Input subsystem

UEnhancedInputLocalPlayerSubsystem::AddMappingContext. Get subsystem via GetEnhancedInputLocalPlayerSubsystem.

Sublevel

A child level streamed in/out of a persistent level. Used for open-world streaming and modular maps.

SpawnSystemAtLocation — spawn a Niagara/Cascade particle system

UNiagaraFunctionLibrary::SpawnSystemAtLocation. bAutoDestroy=true for fire-and-forget. Use SpawnSystemAttached to attach to a component.

Metasound

UE 5.0+ next-gen sound system — node graphs for procedural audio. Replaces Sound Cue for new projects.

Sprint system with stamina drain and recovery

Pattern: Variables bIsSprinting(bool), Stamina(float)=100, MaxStamina(float)=100, SprintSpeed(float)=1200, WalkSpeed(float)=600, DrainRate(float)=20, RecoverRate(float)=10. Sprint pressed: bIsSprinting=true → SetMaxWalkSpeed(SprintSpeed). Released: bIsSprinting=false → SetMaxWalkSpeed(WalkSpeed). Tick: Branch(bIsSprinting) → Stamina -= DrainRate*DT. Else: Stamina += RecoverRate*DT. Clamp(0, Max). If Stamina<=0 → force stop sprint.

Physics Body

A SceneComponent with simulate-physics enabled. Driven by forces, gravity, collisions instead of explicit transforms.

Health and damage system with ApplyDamage and EventAnyDamage

Dealing damage: Event → ApplyDamage(TargetActor, BaseDamage, InstigatorController, DamageCauser, DamageTypeClass). Receiving: EventAnyDamage → Damage output → Subtract_FloatFloat(CurrentHealth, Damage) → FClamp(Result, 0, MaxHealth) → SET CurrentHealth → Branch(CurrentHealth <= 0) → True: DestroyActor. Initialize CurrentHealth=MaxHealth in BeginPlay.