GetGameInstance — get persistent game instance

UGameplayStatics::GetGameInstance. Persists across level loads.

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.

GetGameInstance — get the GameInstance (persists across levels)

Pure node. Ideal for storing data that persists across level loads.

SpawnSoundAtLocation — spawn persistent audio component at location

SaveGame

A class for persisting player progress to disk. Subclass USaveGame, add fields, then SaveGameToSlot / LoadGameFromSlot.

FlushPersistentDebugLines — clear all persistent debug draw

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.

Health regeneration over time with timer

Pattern: Variables RegenRate(float)=5.0, RegenDelay(float)=3.0, RegenTimerHandle. On damage received: ClearTimer(RegenTimerHandle) → SET timer(RegenDelay, RegenTick, looping=true). RegenTick function: Branch(Health < MaxHealth) → True: SET Health = FClamp(Health + RegenRate*DeltaSeconds, 0, MaxHealth). False: ClearTimer.

SetLifeSpan — set actor lifetime before auto-destroy

0 = live forever.

Checkpoint and autosave system with trigger volumes

Pattern: BP_Checkpoint with BoxTrigger, variable CheckpointID(int). OnBeginOverlap(Player) → DoOnce → CreateSaveGameObject(MySaveGame) → SET PlayerLocation, Health, Inventory, CheckpointID → SaveGameToSlot('AutoSave', 0). On death/respawn: LoadGameFromSlot('AutoSave') → Cast → TeleportTo(SavedLocation) → restore Health etc. Show 'Checkpoint Reached' UI briefly.