A roblox custom stealth ai script is basically the holy grail for anyone trying to build a tactical shooter, a horror game, or a classic "sneak-around" mission on the platform. Let's be real: the default Roblox pathfinding is okay for zombies that just mindlessly chase you, but if you want an NPC that actually feels intelligent—someone who patrols, gets suspicious when they hear a footstep, and peers around corners—you have to get your hands dirty with some custom logic.
Creating a stealth system is less about one giant "magic" script and more about layering different systems on top of each other. You've got vision, hearing, and a "brain" that decides what the NPC should be doing at any given moment. When you get it right, it completely changes the vibe of your game. Suddenly, the player isn't just running through a level; they're hugging walls and timing their movements.
Why the Basic Follow Script Doesn't Cut It
If you've ever used a simple Humanoid:MoveTo() script, you know the frustration. The NPC just walks in a straight line toward the player, even through walls, and has zero sense of its surroundings. In a stealth game, that's a total dealbreaker.
A proper stealth AI needs to have "states." Think of it like a flow chart. Most of the time, the NPC is in a Patrol state. If they see a glimmer of the player, they might switch to Suspicious. If they lose you, they go into Searching. This logic is what makes the AI feel like a living character rather than a buggy part of the map. Using a custom script allows you to fine-tune these transitions so the game feels fair but challenging.
Building the "Eyes": Vision and Raycasting
The most important part of any stealth AI is the vision system. You don't want your guards to have 360-degree vision (unless they're literal robots, I guess). You need to define a Field of View (FOV) and then use something called Raycasting to make sure they can actually "see" the player.
In your script, you're basically checking two things. First, is the player within a certain angle in front of the NPC? You can figure this out using the "Dot Product" of the NPC's face direction and the direction to the player. Second, if they are in that cone, is there a wall in the way? This is where workspace:Raycast() comes in.
The script sends out an invisible line from the NPC's eyes to the player's head. If that line hits a part before it hits the player, the guard can't see you. It sounds complicated, but once you get the math down, it's incredibly reliable. Plus, you can tweak the FOV—maybe some guards are more eagle-eyed than others, making the level design much more interesting.
The "Ears": Making the AI Hear You
Stealth isn't just about staying out of sight; it's about staying quiet. A solid roblox custom stealth ai script should definitely include a hearing mechanic.
Instead of checking vision every frame, you can set up a system where certain player actions—like sprinting, jumping, or knocking over a physics object—emit a "sound event." When this happens, the script checks the distance between the noise and any nearby NPCs.
If the guard is close enough to "hear" the noise, you don't necessarily want them to instantly know where you are. Instead, have them walk toward the location of the sound. This creates that classic stealth game tension where the player throws a rock (or a brick, or a taco) to distract a guard and sneak past. It's a simple addition to the code, but it adds a massive layer of depth to the gameplay.
Implementing a Finite State Machine (FSM)
I mentioned "states" earlier, and this is really the backbone of the whole thing. In the coding world, we call this a Finite State Machine. It sounds fancy, but it's just a way to organize what the AI is thinking.
Here's a typical breakdown for a stealth NPC: * Idle/Patrol: The guard follows a set of nodes or just stands still. * Alerted: The guard heard something or saw a "peek" of the player. They stop and look around. * Searching: The guard moves to the last known position of the player and investigates the immediate area. * Pursuit: The guard has a clear line of sight and is actively trying to catch or shoot the player. * Return: If the guard loses the player for long enough, they head back to their original patrol route.
By separating these into functions within your script, it's way easier to debug. If the guard is getting stuck during the search phase, you know exactly which part of the script to look at. It also prevents the AI from looking jittery or confused because it always knows exactly which "mode" it should be in.
Optimizing for Performance
One mistake I see a lot of developers make is running these heavy vision and hearing checks every single frame (60 times a second). If you have one guard, it's fine. If you have twenty, your server is going to start sweating.
To keep things smooth, you can "throttle" the AI. Maybe it only checks for the player every 0.1 or 0.2 seconds. To the player, that's basically instantaneous, but for the server, it's a huge relief. You can also use Magnitude checks to see if the player is even remotely close before running the expensive Raycasting math. If the player is 500 studs away, there's no reason for the guard to be calculating vision cones.
Making it Fair (and Fun)
Let's talk about the "Human" element of the script. If an NPC spots you and instantly kills you, players are going to get frustrated and quit. Realism is cool, but fun is better.
You should build in a Detection Meter. Instead of the AI instantly switching to Pursuit mode, have a variable that fills up the longer you stay in their vision. You can show this to the player with a UI element (like a yellow-to-red arrow). This gives the player a split second to dive back behind cover.
Also, don't forget to give the guards some "forgetfulness." If you hide in a vent for 30 seconds, the guards should eventually give up and go back to their posts. It's a bit unrealistic, but it's a core part of the stealth genre that makes the "cat and mouse" loop actually work.
Integrating with Roblox Tools
The cool thing about writing a roblox custom stealth ai script is that it can interact with everything else in your game. You can hook it up to an alarm system so that if one guard enters the Pursuit state, they trigger a "Global Alert" that makes every other guard on the map more vigilant.
You can also link it to light sources. If the player is standing in a dark area (which you can check by looking at the nearest light parts), you could potentially reduce the NPC's vision range. This makes the environment itself part of the strategy, rewarding players for shooting out lights or staying in the shadows.
Final Thoughts on Scripting Your AI
At the end of the day, there isn't a "one-size-fits-all" script you can just copy-paste and expect to work perfectly for every game. Every project has different needs. A horror game needs slow, stalking AI that builds dread, while a tactical heist game needs snappy, coordinated guards that use cover.
The best way to start is by building the vision system first. Once you can make a guard "see" you and follow you, start adding the layers: the patrol paths, the hearing, the alert states, and finally, the polish. It's a bit of a rabbit hole, but seeing your NPCs behave like actual characters instead of wandering blocks is one of the most satisfying parts of Roblox development.
Don't be afraid to experiment with different detection speeds or search patterns. Sometimes the most "organic" feeling AI comes from adding a little bit of randomness to their movements. Happy scripting, and hopefully, your players find your guards just tough enough to keep them on their toes!