If you've been trying to figure out how a roblox mob script actually functions, you're likely realizing that making an enemy move and attack is a bit more complicated than just telling a part to follow a player. It's one of those things that seems simple on the surface—just make the NPC walk toward the closest person—but once you start building a real game, you run into walls, literally and figuratively. You've got to deal with pathfinding, animations, damage loops, and the ever-present threat of server lag.
Most people start their journey by looking for a "plug and play" script, but those usually end up breaking the moment you try to add a second enemy. If you want your game to feel professional, you really need to understand what's happening under the hood of a solid NPC system.
The basics of the chase
The heart of any roblox mob script is the detection logic. In the simplest terms, the script needs to constantly ask, "Is there a player nearby?" and "Can I get to them?" Most beginners use a while true do loop and a Magnitude check. It's a classic for a reason—it works. You calculate the distance between the mob's primary part and the player's character. If that number is lower than your "aggro" range, the mob starts moving.
But here's where it gets tricky. If you just use Humanoid:MoveTo(), your mob is going to be pretty dumb. It'll walk straight into a wall and keep walking against it like it's trying to phase through the brickwork. That's because MoveTo() is a direct line. To fix this, you have to look into the PathfindingService. This is the "brain" that calculates a series of waypoints around obstacles. It's a bit more intensive on the server, but it's the only way to keep your NPCs from looking like they've lost their minds.
Implementing a simple state machine
One of the biggest mistakes I see in a messy roblox mob script is trying to handle everything in one giant block of code. It becomes a nightmare to debug. Instead, you should think about your mob in "states."
Think of it like this: * Idle: The mob is just standing there or wandering around a small area. * Chasing: The mob has spotted a player and is closing the gap. * Attacking: The mob is close enough to swing a sword or fire a projectile. * Returning: The player got away, and the mob is heading back to its spawn point.
By using a simple state machine, your script becomes way more organized. You can tell the script, "If the state is Chasing, run the pathfinding code." "If the state is Attacking, trigger the animation and deal damage." This prevents the mob from trying to attack while it's still ten studs away or trying to wander off while it's in the middle of a fight.
Why PathfindingService is your best friend
I mentioned it earlier, but we really need to talk about PathfindingService. When you're writing a roblox mob script, you're essentially asking the engine to map out a route. You define the agent parameters—like how tall the mob is and how wide it is—and the service returns a path object.
The secret to making this feel smooth is how you update those waypoints. If you calculate the path once and never again, the player will simply step to the side, and the mob will keep walking to where the player used to be. You need to recalculate, but not too often. Doing it every 0.1 seconds might tank your server performance if you have fifty mobs on the map. Most devs find a sweet spot around every 0.5 to 1 second, or they only recalculate if the player has moved a certain distance away from the last targeted waypoint.
Handling the "Attack" logic
Once the mob actually catches up to the player, you need the roblox mob script to stop moving and start swinging. This is usually handled by a distance check within the main loop. If the distance is less than, say, 5 studs, you trigger the attack.
Don't just subtract health from the player instantly. That feels cheap. You want to load an animation onto the mob's humanoid, play it, and use a "hitbox" system. You could use the .Touched event on the mob's weapon, but that's notoriously unreliable in Roblox. A better way is to use a Raycast or a GetPartBoundsInBox check at a specific moment in the animation (usually using an Animation Event). This ensures the player can actually dodge the attack, which makes your game much more fun to play.
Optimization and the lag problem
Let's talk about the elephant in the room: performance. If you have a hundred mobs all running their own roblox mob script with pathfinding and distance checks every frame, your server is going to scream.
One way to optimize is to handle the "visuals" on the client side. The server should handle the actual position and the "truth" of the mob's health, but things like smooth movement and animations can often be smoothed out on the player's end.
Another trick is to use a "Heartbeat" or "Task" scheduler rather than a bunch of separate scripts. Instead of 100 scripts for 100 mobs, you could have one central script that loops through a folder of mobs and updates them. This reduces the overhead significantly and keeps your code localized in one place. Also, always use task.wait() instead of the old wait(). It's more precise and plays much nicer with the engine's task scheduler.
Making mobs feel alive
A roblox mob script that just makes an NPC walk toward you is boring. To make it feel "alive," you need to add layers. Add some random wandering when they aren't aggroed. Give them different sounds for stepping, growling, and taking damage.
You can also use Raycasting for "Line of Sight." This means the mob won't magically know you're behind a wall. It will only start chasing you if it can actually see your character. This adds a level of stealth to your game. If a player ducks behind a crate, the mob might walk to the last place it saw them, look around for a second, and then return to its idle state. It sounds complicated, but it's just a few extra lines of logic that make a world of difference.
Dealing with health and death
Finally, the roblox mob script needs to know when to quit. You'll want to connect to the Humanoid.Died event. When the mob dies, you should probably disable the AI script, play a death animation, and then wait a few seconds before destroying the model or respawning it.
This is also the perfect time to handle loot drops. You can have a simple table in your script with item names and percentages. When the Died event fires, the script picks an item based on the weights you set and spawns it at the mob's position.
Final thoughts on scripting mobs
Building a solid roblox mob script is a bit of a rite of passage for Roblox developers. It forces you to learn about vectors, services, performance management, and game design all at once. It's rarely perfect on the first try. You'll probably see your mobs walking through floors or flying into the sky at least once during the process.
The key is to keep it modular. Don't be afraid to break things and try again. Start with a simple follow script, then add pathfinding, then add states, and then polish the animations. Before you know it, you'll have a combat system that feels responsive and challenging rather than just a bunch of parts sliding around on the baseplate. Happy coding, and don't let the bugs (or the mobs) get you down!