🔺 My First Unreal Game · Episode 8 of 9 · See All Episodes
🦊Lumo says: take this episode one step at a time. Finish the build, answer the check, and your progress saves on this device.
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⚡ Episode 8 · Advanced · Systems That Scale

Power User!
Advanced Systems

The systems that separate demos from games: clean Blueprint communication (interfaces & dispatchers), a component-based health system, save games, level streaming and performance profiling.

👶 Ages 12+ ⏱️ ~2.5 Hours 🔺 Unreal Engine ✓ Free
🔌 BP interfaces 📣 Event dispatchers 🧩 Actor components 💾 SaveGame objects 🌊 Level streaming 📊 Profiling
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Before you start: this episode assumes Unreal Engine 5 is already installed and you have a project from the earlier episodes, so new here? Start at Episode 1: Blueprint Basics. Unreal is a big install (around 30 GB) that wants a strong PC with a dedicated GPU. This is a home-computer workshop, so a grown-up should help, and it will not run on a locked-down school computer. Want to practise with nothing to install? Use the Unreal Studio in your browser.
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Workshop reference pack: download an offline copy of every step in this workshop: ⬇ unreal-advanced-workshop-reference.zip. Every code block also has a Copy button.
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Blueprint Interfaces
Talk to anything without casting to everything
Active
🎯
Goal for this step

Replace cast-spaghetti with a clean Interact interface.

  • 1The problem: your player casts to BP_Door, BP_Chest, BP_NPC, BP_Lever… every new interactable means editing the player. Spaghetti.
  • 2The fix: a Blueprint Interface (BPI_Interact) with one function: Interact.
  • 3Each interactable implements it its own way: door opens, chest loots, NPC talks. The player just sends Interact (Message) at whatever it traces, no casts, no knowledge of types.
  • 4Add interact detection: a line trace forward from the camera on E press; send the interface message to the hit actor.
  • 5New interactable tomorrow? Implement the interface. Player code: unchanged. THAT is architecture.
✏️
Fill in the Blanks
+15 XP
A Blueprint defines functions many different actors can implement. The caller sends a without needing a single node.
🧠
Knowledge Check
+15 XP
The interface saves you from…
AUsing variables
BA cast-per-type pile in the player that grows forever, instead, anything answering "Interact" just works
CSlow rendering
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📣
Event Dispatchers
Broadcast events without knowing who listens
Locked
🎯
Goal for this step

Decouple systems with the observer pattern, Unreal-style.

  • 1Problem two: the boss dies → update HUD, open gate, play music, grant achievement. Should the boss know about ALL those? No!
  • 2Event Dispatcher on the boss: OnBossDied. The boss just Calls it when hp hits 0, and has no idea who cares.
  • 3The HUD, the gate and the music manager each Bind to it at BeginPlay (get boss reference → Bind Event to OnBossDied).
  • 4One broadcast, any number of listeners, zero coupling. This is the observer pattern, MonoBehaviour events/C# delegates/JS addEventListener are all the same idea.
  • 5Refactor your coin pickup to use one: OnCoinCollected → the HUD binds instead of the coin writing player variables.
✏️
Fill in the Blanks
+15 XP
An Event lets an actor broadcast without knowing its listeners, who to it at BeginPlay. This is the classic pattern.
🧠
Knowledge Check
+15 XP
Dispatchers point dependencies in the healthy direction, meaning…
AEverything references everything
BListeners know the broadcaster; the broadcaster knows NOBODY, the boss ships without knowing a HUD exists
CThe HUD owns the boss
3
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Actor Components
A reusable HealthComponent for player, enemies, crates
Locked
🎯
Goal for this step

Package health as a component any actor can wear.

  • 1Health for player, enemies AND breakable crates, copy-paste three times? Never. Build an Actor Component: BP_HealthComponent.
  • 2Inside it: MaxHealth + CurrentHealth variables, a TakeDamage function, and two dispatchers, OnDamaged and OnDied.
  • 3Any actor adds the component and binds the events: the player’s OnDied → respawn logic; the crate’s OnDied → spawn loot + destroy.
  • 4Same component, wildly different owners. Composition over duplication, Unity components, Unreal components, same philosophy.
  • 5Wire your Episode-series weapons to call TakeDamage on anything with the component (FindComponentByClass → valid check).
✏️
Fill in the Blanks
+15 XP
Reusable behaviour is packaged in an Actor . The health component announces state through its OnDamaged and dispatchers, letting each owner respond .
🧠
Knowledge Check
+15 XP
The crate and the player share health logic but die differently because…
ACrates are weaker
BThe component OWNS the numbers; each actor binds its own reaction to OnDied, logic shared, response custom
CTwo components exist
4
💾
Save Games
SaveGame objects, slots, and save-on-checkpoint
Locked
🎯
Goal for this step

Persist progress to disk the Unreal way.

  • 1Create a Blueprint class from SaveGame: BP_MySave, with variables: PlayerLocation, CoinCount, Health, LevelName.
  • 2Saving: Create Save Game Object → fill its variables from the world → Save Game to Slot ("slot1").
  • 3Loading: Does Save Game Exist → Load Game from Slot → cast to BP_MySave → apply values (teleport player, set counts).
  • 4Trigger saves at checkpoints (a trigger volume calling a SaveGame function in the Game Mode) and load from the main menu Continue button.
  • 5Test the full loop: play, collect, save, QUIT COMPLETELY, relaunch, continue. Progress intact = players trust your game.
✏️
Fill in the Blanks
+15 XP
Persistent data lives in a class derived from , written with Save Game to and read back with Load Game from Slot after checking it .
🧠
Knowledge Check
+15 XP
The SaveGame object pattern mirrors which save you built earlier?
ANothing similar
BThe GML JSON save struct, gather meaningful state into one object, serialise it, restore it on load
CThe Unity scene reload
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🌊
Level Streaming
Big worlds that load in pieces
Locked
🎯
Goal for this step

Split a map into streaming sublevels loaded on demand.

  • 1One giant level = huge load times and memory. Real games STREAM: the world is sublevels loaded/unloaded as needed.
  • 2Window → Levels: create sublevels (Zone_A, Zone_B), move geometry into them (select actors → Move Selection to Level).
  • 3Trigger volumes at zone borders: Load Stream Level (the one ahead) and Unload Stream Level (the one behind).
  • 4Hide the seam: doorways, corridors and elevators, every "mysteriously slow door" in AAA games is a streaming mask!
  • 5Watch memory drop in the stats while zones unload. Same idea as UE5’s World Partition, learned by hand.
✏️
Fill in the Blanks
+15 XP
Large maps are split into managed in the Levels window, loaded with Load Level. Corridors and slow doors exist to hide .
🧠
Knowledge Check
+15 XP
Elevators and squeeze-through-gap corridors in AAA games usually exist because…
ALevel designers love them
BThey mask streaming, the next zone loads while you are held in a controlled space
CPlayers need rest
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📊
Profiling & Optimisation
stat commands, Unreal Insights, and fixing the real problem
Locked
🎯
Goal for this step

Measure performance properly and apply the right fixes.

  • 1The golden rule: measure before optimising. Feelings lie; profilers do not.
  • 2Console (backtick key): stat fps, stat unit, is the frame spent on Game (your logic), Draw (CPU render prep) or GPU (shading)?
  • 3GPU-bound: heavy materials/lights/resolution. Game-bound: your Blueprints, usually Tick abuse!
  • 4Tick medicine: does that coin REALLY need Event Tick? Rotating meshes → a RotatingMovement component (C++-fast); timed logic → Timers, not Tick counting.
  • 5Try Unreal Insights (bundled) for a full flame-graph trace. Fix the top item only, re-measure, repeat. That loop is the whole discipline.
✏️
Fill in the Blanks
+15 XP
The console command stat splits frame time between Game, Draw and GPU. The most common Blueprint performance sin is overusing Event . Always before optimising.
🧠
Knowledge Check
+15 XP
stat unit shows Game 30ms, GPU 8ms. Where do you optimise?
AReduce resolution
BYour game logic/Blueprints, the CPU game thread is the bottleneck, the GPU is idling
CBuy a new monitor
🎉🏆🎮✨🎉
Workshop Complete!
Interfaces, dispatchers, components, saves and profiling, architecture skills that scale to shipped games. The multiplayer finale is next!
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Episode 9: Multiplayer Basics →
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🧩
Code Order: Blueprint Game Flow
+20 XP
Drag these Blueprint steps into the correct order for setting up player input and movement.
Get the input axis value from the Enhanced Input Action
Create a new Blueprint class that extends Character
Connect the result to Add Movement Input
Add an Input Mapping Context in BeginPlay
Multiply axis value by speed to get movement direction