Getting your roblox stealth mechanics script detection right is honestly one of the hardest parts of making a polished sneaker or horror game. If the detection is too sensitive, players get frustrated and quit because it feels like the NPCs have wallhacks. If it's too lenient, the game becomes a cakewalk, and there's no tension. Striking that perfect balance requires a mix of clever raycasting, performance optimization, and a solid understanding of how Roblox handles server-client communication.
When we talk about "script detection" in this context, we aren't just talking about anti-cheats—though that's a part of it. We're talking about the logic that allows an NPC to "detect" a player through various scripts. It's the invisible math happening behind the scenes that determines if a guard turns around just as you're sneaking past or if they stay oblivious while you're crouching in a corner.
The Foundation: Raycasting for Vision
The absolute bread and butter of any stealth system is raycasting. If you don't get your rays right, your NPCs are basically blind or, conversely, all-seeing gods. In Roblox, WorldRoot:Raycast is your best friend here. You basically fire an invisible line from the NPC's eyes toward the player. If that line hits the player before it hits a wall or a crate, the player is "seen."
But you can't just fire rays every single frame for every NPC. That's a one-way ticket to Lag City, especially if your server is hosting thirty players and fifty guards. To keep your roblox stealth mechanics script detection efficient, you should only fire that raycast if the player is already within a certain distance and a certain angle.
I usually start with a simple distance check using .Magnitude. If the player is more than 50 studs away, don't even bother with the raycast. If they are close enough, then check the angle using the Dot Product. If they're behind the guard, they're safe (unless the guard has ears, but we'll get to that). Only when they pass those two tests do you run the expensive raycast to check for physical obstructions.
Using the Dot Product for Field of View
A common mistake I see in beginner stealth scripts is giving NPCs 360-degree vision. It's lazy and it ruins the gameplay. To fix this, you need to use the Dot Product of the NPC's look vector and the vector pointing toward the player.
Basically, you're calculating how much two directions "overlap." If the result is close to 1, the player is directly in front of the NPC. If it's 0, they're to the side. If it's -1, they're behind them. By setting a threshold—say, 0.5—you can create a cone of vision. This makes the roblox stealth mechanics script detection feel much more natural. It allows players to actually "sneak" up behind enemies, which is, you know, the whole point of a stealth game.
Making Detection "Sticky" with States
In a good stealth game, detection isn't an "on or off" switch. It's a meter. If a guard catches a glimpse of you for 0.1 seconds, they shouldn't immediately pull out a shotgun and start blasting. They should get suspicious first.
You can handle this by using a state machine in your script. I like to use four main states: 1. Idle: The guard is on a patrol path and totally unaware. 2. Suspicious: The guard saw something or heard a noise. They stop and look toward the source. 3. Searching: The guard moves toward the last known position of the player. 4. Alert: The player is fully detected, and the guard engages.
By adding a "detection meter" that fills up over time based on how visible the player is, you give the player a chance to duck back into cover. It adds that heart-pounding "Oh no, he saw me!" moment that makes stealth games fun. If the player is crouching, the meter fills slower. If they're standing in bright light, it fills faster.
Adding "Ears" to the NPCs
Vision is only half the battle. If I'm sprinting right behind a guard on a metal floor, he should probably hear me. Integrating sound into your roblox stealth mechanics script detection adds a whole new layer of depth.
You don't actually have to use Roblox's sound engine for this logic. Instead, you can create a "noise" variable on the player. If they're walking, noise is 5. If they're sprinting, it's 15. If they're crouching, it's 0. The NPCs then check for any "noise" within a certain radius. If the noise level is higher than the distance between the NPC and the player, the NPC switches to the "Suspicious" state. It's simple, it's fast, and it works like a charm.
Optimization and Performance Hurdles
One thing people often overlook is how heavy these scripts can get. If you have twenty NPCs all running detection loops every 0.1 seconds, you might start seeing some frame drops on lower-end devices.
One trick I use is "staggering" the checks. Instead of all NPCs checking for players at the exact same time, you can add a tiny random delay to each loop. Also, consider using task.wait() instead of wait() for better precision.
Another big performance win is offloading some of the purely visual stuff to the client. The server should handle the actual "Am I caught?" logic to prevent cheating, but the client can handle the "Detection Meter" UI and the red glowing eyes on the guards. This keeps the server responsive while making the game look smooth for the player.
Preventing Exploits in Stealth Scripts
Since we're talking about roblox stealth mechanics script detection, we have to mention the players who try to break it. Exploiter scripts love to mess with local variables to make themselves invisible to NPCs.
If you put your detection logic entirely in a LocalScript, an exploiter can just delete that script, and your guards will become brain-dead statues. Always, always keep the core detection logic on the server. The server should be the one saying "I see Player1," not the player's computer telling the server "Hey, I'm being seen."
Sure, there might be a tiny bit of latency, but it's worth it for the security. You can compensate for the lag by making the raycasts a bit more generous or using a slightly larger hit box for the player on the server side.
Environmental Factors and Visibility
To really take your script to the next level, you should think about the environment. Is the player in a dark room? Are they standing behind a semi-transparent glass pane?
You can use RaycastParams to filter out certain objects, but you can also check the Material of the part the player is hiding behind. If the raycast hits a part with a high transparency, maybe the detection meter fills up 50% slower instead of being blocked entirely.
Lighting is a bit trickier in Roblox because there isn't a super easy way for a script to know "how much light" is hitting a specific point without some complex math or using a hacky workaround like checking the distance to the nearest light source. But even a simple distance-to-light check can make your roblox stealth mechanics script detection feel way more immersive.
Wrapping Things Up
Building a robust stealth system is a marathon, not a sprint. It takes a lot of tweaking and playtesting to get the numbers feeling right. You'll probably spend hours just adjusting the speed at which a detection meter fills up or the exact angle of an NPC's peripheral vision.
Just remember to keep your code clean, use raycasting smartly, and always keep the server in charge of the important decisions. Once you get the hang of it, you'll find that these mechanics can be applied to way more than just stealth games—they're great for AI in shooters, horror games, and even NPC interactions in RPGs. Keep experimenting with your scripts, and don't be afraid to break things to see how they work!