If you've been hunting for a roblox custom stealth ai script that doesn't just make your NPCs stare blankly at walls, you've probably realized that most public scripts are either too simple or way too broken. Building a stealth system is one of those things that looks easy on paper but gets complicated the second you want an NPC to actually feel "smart." You want them to hunt the player, lose track of them when they hide, and get suspicious when they hear a footstep—not just instantly lock on like they've got thermal goggles and a grudge.
The real magic behind a great stealth game isn't just the player's movement; it's how the AI perceives the world. If the AI is too perfect, the game is frustrating. If it's too dumb, there's no tension. To get it right, you have to break down the AI's "brain" into a few key systems: vision, hearing, and state management.
The logic of vision and raycasting
The most basic part of any roblox custom stealth ai script is vision. You can't just check the distance between the NPC and the player, because that would mean the NPC can "see" through solid brick walls. That's where raycasting comes in. Think of a raycast like an invisible laser beam shot from the NPC's eyes toward the player. If that laser hits a wall first, the NPC can't see you. If it hits the player's torso, the chase is on.
But vision shouldn't be 360 degrees unless you're making a horror game about an eldritch monster with eyes on the back of its head. You need a Field of View (FOV). In Luau, you can use the dot product to figure out if a player is within a certain angle in front of the NPC. Usually, an 80 to 90-degree cone feels fair. It gives the player a chance to sneak up behind the guard for a takedown, which is exactly what makes stealth games fun.
Adding the sense of hearing
Vision is great, but a truly immersive roblox custom stealth ai script needs to account for sound too. If a player is sprinting right behind an NPC, that NPC should probably turn around. You can handle this by checking the player's MoveDirection.Magnitude and their distance.
A cool way to do this is to have a "noise level" variable. If the player is crouching, their noise is near zero. If they're sprinting, it's high. You can even tie this into the environment. Maybe walking on metal grates makes more noise than walking on carpet. When the AI "hears" a noise, instead of immediately attacking, you should make them move toward the source of the sound to investigate. This creates those "did he hear me?" moments that keep players on edge.
Managing AI states: Idle, Suspicious, and Alert
You don't want your AI to just be "on" or "off." It needs layers. A solid roblox custom stealth ai script usually operates on a State Machine. This is just a fancy way of saying the NPC has different "modes" of behavior.
The Idle state
This is where the NPC just hangs out. Maybe they're standing at a post or walking a pre-set patrol path using PathfindingService. They aren't looking for anyone specifically, but they're keeping their "eyes" open.
The Suspicious state
This is the middle ground. Maybe they saw a glimpse of the player or heard a box fall. Instead of sprinting toward the player, the NPC should stop, look toward the noise, and maybe mutter a line of dialogue. They might walk over to the spot where they last saw/heard something. If they don't find anything after a few seconds, they go back to their patrol.
The Alert and Chase state
This is full-on combat mode. The NPC has spotted the player and is now actively pursuing them. In a stealth game, you also need a "Lost" state. If the player turns a corner and hides in a locker, the NPC shouldn't just know where they are. They should go to the last known position, look around for a bit, and then eventually give up.
Performance and optimization
One thing developers often forget when writing a roblox custom stealth ai script is how much it can lag a server if you have fifty NPCs all raycasting every single frame. You really don't need to check vision 60 times a second. Checking every 0.1 or 0.2 seconds is usually plenty and saves a ton of processing power.
Also, be careful with PathfindingService. Generating a new path every frame is a recipe for a laggy mess. It's better to compute a path once and only re-calculate it if the player has moved a significant distance from their last known position.
Making it feel fair for the player
There's a concept in stealth design called "coyote time" or "grace periods." Basically, if an NPC spots a player, don't have the "detected" meter fill up instantly. Give the player a split second to duck back behind a crate. You can do this by adding a detection bar that fills up over time based on how close the player is and how well-lit the area is.
If you're building a roblox custom stealth ai script, consider adding a "hidden" status. If the player is sitting in a specific "Darkness" zone or inside a "Bush" part, you can multiply the AI's detection speed by zero. This makes the environment part of the gameplay, rather than just decoration.
Why custom scripts beat toolbox versions
It's tempting to just grab a kit from the Roblox Toolbox and call it a day. But those kits are usually bloated with features you don't need, or they're coded in a way that makes them impossible to tweak. When you write your own roblox custom stealth ai script, you have total control.
Want the guards to call for backup when they see you? You can code that. Want them to get distracted by a coin you throw? Easy. When you build the logic yourself, you aren't fighting someone else's messy code. You're building a system that fits your specific game's vibe. Plus, you'll actually understand how it works when it inevitably breaks (because let's be real, game dev is mostly just fixing things you broke five minutes ago).
Final thoughts on implementation
Setting up a high-quality roblox custom stealth ai script takes a bit of patience. You'll spend a lot of time watching your NPCs walk into walls or ignore you while you're standing right in front of them. But once you get that loop of "Detect -> Investigate -> Chase" working smoothly, it completely changes the feel of your game.
Start small. Get the vision working first. Then add the patrol paths. Then add the sound detection. Before you know it, you'll have a stealth system that feels just as professional as a triple-A title, all within the Roblox engine. Just remember to keep the player's experience in mind—the goal isn't to make an AI that's impossible to beat, but one that's fun to outsmart.