Team Context
The AI system was developed for Project Cas9, a horror game project created by a team of seven where I worked as Lead Programmer. The main enemy needed to create interesting gameplay on its own without relying on many scripted events or additional gameplay systems.
I built the monster AI to handle perception, searching, chasing, and attacking, while a separate AI Director controls the overall pressure around the player. Inspired by Alien: Isolation, the two systems work together to create encounters without giving the monster constant knowledge of the player’s position.
The goal was to make the enemy unpredictable enough to carry the main gameplay, while still following clear rules that could be adjusted and debugged.
Responsibilities
Get Search and Investigation Behavior
Target is Responsibility
Built a Behavior Tree that lets the monster investigate targets, search designer-placed points, look around rooms, chase the player, and return to searching after losing them.
Custom Sight and Detection
Created a vision system with multiple view cones, partial visibility checks, detection buildup, and a combined detection level that uses both sight and hearing.
Custom Hearing System
Developed a shared hearing subsystem with sound emitters and Ear Components that takes sound range, movement speed, distance, walls, and paths around obstacles into account.
Get AI Director and Encounter Pacing
Target is Responsibility
Built an AI Director that tracks how tense of the current situation is and moves the monster closer or further away to control the amount of pressure on the player.
System Overview
The system separates the monster’s immediate decisions from the overall encounter pacing. The monster uses its own senses to detect sounds and visible targets. This information is passed into the Behavior Tree, where it can investigate, search, chase, or attack. The AI Director does not directly control every action. It watches the relationship between the monster and player and sends larger movement commands when the encounter has been too quiet or too intense.
High-Level Architecture
Perception & Detection
Search & Chase Behavior
AI Director & Encounter Pacing
Highlights
Search & Investigation
Custom Hearing
Detection & Perception
AI Director
Context
The monster does not always know where the player is. After seeing or hearing something, it moves toward the last known location and searches nearby designer-placed points.
Search Points can tell the monster to visit a location or only look toward it. Their priority and some randomness are used to create different search paths each time.
Visualization
Search Path Visualization
UE Editor
The monster searches designer-placed points around its last known target instead of directly tracking the player at all times.
Combining Different Senses
Sight and hearing build detection in different ways. I needed to combine both values while still keeping track of which target the monster should react to.
Challenge
Unpredictability vs Designer Control
Random behavior made the monster less predictable, but too much randomness could feel unfair. Designer-placed Search and Spawn Zones kept it controlled.
Tradeoff
Impact
Created a monster that can search, investigate, chase and hear the player instead of always knowing their position.
Gave level designers control over search and spawn areas.
Improved encounter pacing by separating the monster’s behavior from the AI Director.
Added debug visualization for vision cones, visibility traces, sound bubbles, hearing ranges, search paths, Menace, and Safe Time.
Created reusable hearing components that can also be used by other AI characters.
What I Learned
Horror AI is not only about finding the player. The timing between encounters is just as important as the chase itself.
Splitting perception, monster behavior, and encounter pacing into separate systems makes each part easier to adjust.
Random behavior works better when it is limited by designer-controlled zones, points, and priorities.
Debug visualization is important for AI because most perception and decision-making cannot normally be seen.
What I Would Improve
Add a debugger that shows the current state, interest target, chase target, detection values, and Director command directly as text above the AI.
Improve search-path generation so it avoids repeating nearby points and considers where the player was last seen or heard.
Add material- and portal-based sound propagation for different walls, doors, and connected rooms.
Move more monster and Director settings into reusable tuning profiles for different levels or difficulty modes.
Improve the Director so it can react to player habits, hiding behavior, and repeated routes.
Connect monster vocal sounds and music more closely to its current behavior and Director Menace.