Mobile Programs

Mobile programs (mob progs) are scripts attached to NPCs (mobiles) that bring them to life with custom behavior. They are the most commonly used script type in Sentience.

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What Are Mobile Programs?

A mobile program is a block of scripting code that runs when a specific event occurs — a player enters the room, says a keyword, gives an item to the NPC, or any of dozens of other triggers. The script executes commands as if the NPC were performing actions: speaking, moving, loading objects, transferring players, dealing damage, and more.

Every command in a mob prog is prefixed with mob — for example, mob echo, mob transfer, mob oload. This tells the engine that the NPC is performing the action.

When to Use Mob Programs

Mob programs are ideal for:

  • NPC behavior — Random idle actions, reactions to the environment, ambient dialogue
  • Quest givers — NPCs that check player progress, hand out items, and advance quest stages
  • Shopkeeper customization — Custom greetings, special trade logic, restricted access
  • Combat AI — Bosses with HP-phase transitions, special attacks, self-healing, adds
  • Guards and patrols — NPCs that check for certain items or tokens, transfer intruders, respond to speech
  • Interactive NPCs — Conversation trees using speech triggers, bribe-based services, give-and-receive exchanges

How Mob Programs Work

Every mob prog has three parts:

  1. The script — A block of code stored in the area file (identified by vnum)
  2. A trigger — The event that causes the script to run (e.g., greet, speech, fight)
  3. An attachment — The link between the script, the trigger, and the specific NPC

When the trigger event occurs, the engine runs the script with context about what happened — who triggered it, what they said, what object was involved, etc. Your script accesses this context through variables and quick codes.

Creating a Mob Program with mpedit

The mpedit editor is used to create, edit, and manage mob programs. Here is a typical workflow:

Step 1: Create the Script 

mpedit create

This creates a new mob program and opens the editor. You will see the program’s assigned vnum.

Step 2: Name the Script

Give it a descriptive name so you can identify it later:

name Guard greet script

Step 3: Write the Code

Enter the code editor:

code

This opens a line-based text editor. Type your script, then type . on a blank line to finish:

say Halt! State your business, $n.
mob echoaround $n The guard eyes $n suspiciously.
.

Comments in scripts use the ** prefix, not //. Place comments on their own line:

** This script fires when a player enters the room
say Welcome, $n!

Step 4: Compile the Script

After writing code, the script is automatically checked when you finish editing. If there are syntax errors, you will see them in the editor output.

Step 5: Attach a Trigger to the NPC

Use medit (the mobile editor) to attach the script to an NPC with a trigger:

medit <mob vnum>
addprog <script vnum> <trigger type> <phrase>

For example, to make a mob greet every player who enters:

addprog 12345 greet 100

This attaches script 12345 with a greet trigger and phrase 100 (100% chance of firing).

Step 6: Test

Reset the area or repop the mob, then interact with it to verify the script fires correctly. Use stat mob <name> to confirm the program is attached, and mpstat <name> to see all attached programs.

Mob-Specific Capabilities

Mobile programs have access to capabilities that other script types do not:

Capability Description
mob appear / mob disappear Toggle NPC visibility
mob kill Initiate combat with a target
mob assist Join another character in combat
mob hunt Track and pursue a target across rooms
mob take Take an object directly from a character
mob teleport Teleport all characters in the room
mob chargemoney Deduct coins from a player’s inventory
mob remember / mob forget Store and recall a target character
mob flee Flee from combat

Mob programs also have the widest trigger selection of any entity type — 153 triggers covering movement, combat, speech, commerce, quests, and more.

Script Comments

Use ** at the start of a line to write a comment. Comments are ignored when the script runs:

** Check if the player has the quest token
if tokenvalue $n 50100 0 >= 1
  say Welcome back, hero!
else
  say I don't know you. Begone!
endif

Quick Reference

Topic Link
All mob triggers (153) Triggers
All mob commands (167) Commands
Practical examples Examples
Shared commands reference Shared Commands
Variables and quick codes Variables and Tokens
If-checks and conditions If-Checks Reference
Scripting basics Scripting Basics

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