#41 Behavior Tree Tasks & Blackboard Decorators - How to Make a Ghost Hunting Game in Unreal

In this lesson, we continue building the Ghost AI for our Unreal Engine 5 ghost hunting game and expand the Behavior Tree with Blackboard decorators and the first working AI tasks. In the previous video, we created the base ghost enemy, the Blackboard, and the main Behavior Tree structure. Now we start turning that structure into real decision logic. The ghost should not just pick random branches — it needs conditions that decide when it can chase the player, move to the last seen location, investigate sounds, start ghost events, interact with the environment, or roam around. We begin by adding Blackboard decorators to the main Behavior Tree branches. These decorators control when each sequence is allowed to run. For example, the ghost can only chase the player if it can currently see the player. It can only move to the last seen player position if that location is known. It can only investigate sounds or electronics if it has heard a signal. After that, we add decorators for the passive ghost activity branch. This lets the ghost check whether it can start a ghost event, interact with something in the environment, or roam to another location. Then we create the first Behavior Tree tasks. These tasks will later become the building blocks for the full ghost AI. We prepare tasks for updating the last seen player location, setting chase speed, setting search speed, starting random ghost events, starting interactions, and determining a target location. Next, we implement the first real task logic. The Update Last Seen Player Location task reads the player actor from the Blackboard, gets the player location, stores it as the last seen player position, and updates the matching Blackboard boolean so the Behavior Tree knows this information is available. We also create speed tasks for the ghost. The chase speed is used when the ghost is actively hunting and chasing the player, while the search speed is slower and used when the ghost is looking around or moving toward a known position. By the end of this video, our Behavior Tree is much closer to becoming a working AI system. The ghost now has conditions for choosing behavior and the first tasks that actually write data into the Blackboard and control movement speed. What you will learn in this video: How to add Blackboard decorators to Behavior Tree branches How to control chase, search, sound, interaction, and roaming behavior How to create custom Behavior Tree tasks How to update Blackboard values from a task How to store the last seen player location How to set Blackboard booleans from AI logic How to change ghost movement speed through the Behavior Tree How to separate chase speed from search speed How to prepare the next layer of ghost AI behavior Chapters: 0:00 Intro & Behavior Tree Goal 0:30 Adding Blackboard Decorators to Hunt Logic 1:55 Adding Decorators to Passive Ghost Activity 3:12 Creating the First Behavior Tree Tasks 5:25 Adding Hunt Search and Movement Tasks 7:36 Preparing Passive Ghost Tasks 10:03 Reviewing the Behavior Tree Structure 11:06 Planning the Idle Behavior Issue 12:27 Building Update Last Seen Player Location 17:23 Creating the Chase Speed Task 19:18 Creating the Search Speed Task 20:06 Final Result & Next Step Course Goal: We are building a first-person ghost hunting horror game in Unreal Engine 5 step by step. The project includes player movement, multiplayer, interaction systems, inventory, equipment, ghost hunting tools, evidence systems, ghost AI, sanity, investigation gameplay, and a complete horror game loop. #UnrealEngine5 #UE5 #UnrealEngine #GhostHuntingGame #HorrorGame #BehaviorTree #Blackboard #GhostAI #BehaviorTreeTasks #BlackboardDecorators #EnemyAI #UE5Blueprints #BlueprintTutorial #HorrorGameDevelopment #IndieGameDev #FirstPersonHorror #PhasmophobiaInspired