RuneScript

RuneScript is a scripting language that Jagex uses to create content for RuneScape. The game engine is not written in RuneScript, but instead Java. RuneScript was developed by Jagex Ltd. to allow their other staff that do not know Java to add and edit content for the game. The game engine reads RuneScript files and executes them accordingly. This is the structure most larger programs (such as other video games) follow.

This scripting language is similar to the wiki markup used for articles on this site. RuneScript is parsed into Java for the computer to read just as certain syntax in MediaWiki markup is translated into HTML (e.g. [[page]] changes to the HTML code <a href="/wiki/Page" title="Page">page</a>).

“	We write in a scripting language called RuneScript, which our Game Engine team has created specifically for making RuneScape content. The Java-based game engine then reads this RuneScript code and makes it all work. RuneScript is constantly being changed and expanded as we add new features to it to allow it to do new things."	”
	— Mod John A New Dwarf Quest: Coding and Writing

RuneScript sample from the Biohazard quest

“	Hmm, syntax wise it's similar to any C-style language, except variable names are prefixed with their type (eg. %varname is an integer). We also lack full array support. Other than that, it'd do pretty much anything you could do in C or Java.	”
	— Mod Chris E Game Engine Q&A

The minor updates are usually for introducing a new map and adding new NPCs, and for these updates, a RuneScript file is added into the program. The major updates are for the source code, which is usually for making large changes such as introducing new areas in RuneScape, new skills, or for bug fixes.