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RPG Maker MV CoreScript


"RPG Maker MV CoreScript" is a game engine for 2D games that runs on the browser. "RPG Maker MV CoreScript" is designed as a game engine dedicated to "RPG Maker MV", the latest work of "RPG Maker" series of 2DRPG world number one software with more than 20 years history, and more than 1000 games are running. (February 2017)

What is this project?

This project is a project aimed at improving "RPG Maker MV CoreScript" better by the community and supporting many game creators.

The core script developed by this project is widely distributed to RPG Maker users through KADOKAWA. The RPGMaker MV community is centered around plugins. Therefore, Ver1 series is developed while minimizing destructive change.

How to use

There are three releases

  • Develop --- Development version. You can download it with GitHub.
  • RC --- Release candidate version. It is for game developers to do the test. It will be distributed from game posting site "RPG Atsumaru".
  • Stable --- Stable version. KADOKAWA is widely distributed to general users through Steam and official website.

How to build

To build Corescripts, install Node.js, change working directory, and just type in console:

npm install
npm run build

Then you can find Corescripts in folder “dist”

If you want to build indivisually, Here’s some command,

npm run build:core
npm run build:managers
npm run build:objects
npm run build:scenes
npm run build:sprites
npm run build:windows

To test, place MV’s project in game/ and type

npm test

There are helpful tasks, watch and start.

Watch task is watching js/rpg_*** changes, concat them, and copy that to ./game/js/ .

npm run watch

Start task starts local server. You can test Corescripts in your browser.


npm start

How to join


Development will be done according to the roadmap. Currently we are developing ver 1.2

ver 1.0

Goal: Publish community development version

  • Split core script file
  • Put on github
  • Publish roadmap

ver 1.1

Goal: Fix a fatal bug

  • Fix memory related problems
  • Preceding reading of image material
  • Responding to sound problems of google Chrome
  • Fixed bugs already known

ver 1.2

Goal: Responding to problems where games can not continue

  • Retry at load error
  • Development of a standard plugin for options
  • Volume Change API

ver 1.3

Goal: Assist in game development

  • AutoSave
  • Simple conflict check for plugins
  • Guidelines and sample writing for plugins
  • Refined bug report

ver 1.4

Goal: Accelerate speed, reduce experience time

  • High-speed loading of sound source
  • Progress bar on load screen
  • Lightweight Save File

ver 1.5

Goal: Improve UI

  • Multilingual
  • Multi-touch
  • Battle system touch compliance
  • Touch correspondence of basic system such as equipment


The core script is finally output to mainly 6 files.

Wrapper classes of Pixi.js and base classes such as audio and input processing.
Static classes named XxxManager that manage the game overall.
Classes named Game_Xxx dealing with game data (many are saved).
Classes named Scene_Xxx in which the scene is defined.
Classes named Sprite_Xxx related to image display and processing.
Classes named Window_Xxx handling window display and input.

In addition, a plugin list is defined in plugins.js, and main.js launches the game.

Inheritance style

// In JavaScript this function is constructor
function Derived() {
    this.initialize.apply(this, arguments); // Delegate to initialize()

Derived.prototype = Object.create(Base.prototype); // Derived inherits from Base
Derived.prototype.constructor = Derived;

Derived.prototype.initialize = function () {; // This makes super.initialize() sense

Global variables

Variables named $dataXxx are read from JSON in the data folder. These files are changed by the editor, but they are immutable during play. Variables named $gameXxx are instances of the class defined in rpg_objects.js. When saving the game, these objects (except $gameTemp, $gameMessage, $gameTroop) are serialized to JSON and saved. When loading, since the prototype chain is reconnected simultaneously with deserialization, you can continue using instance methods.

Scene graph

The scene graph is a drawing tree like FLASH provided by Pixi.js. Children are influenced by parent's coordinates and visibility. Register a child in the form (scene or sprite or window).addChild(child).


In RMMV the scene is the root element of the scene graph and has children with Sprite and Window. The life cycle is managed by SceneManager, and it operates up to one at the same time.

Life cycle: new Scene_Xxx() -> create() -> start() -> update()* -> stop() -> terminate()



  1. When the page is loaded, call (main.js)
  2. Initialize classes such as Graphics, WebAudio, Input, TouchInput.
  3. Set Scene_Boot to SceneManager.
  4. Register SceneManager.update in requestAnimationFrame.

requestAnimationFrame is called by the browser at regular time intervals (every time drawing is required).


  1. requestAnimationFrame calls SceneManager.update().
  2. Process the current scene every 1/60 second according to the scene lifecycle rule
  3. If Scene_Xxx.update() is called, then
    1. Call all children update().
    2. Children recursively call their children update().
  4. Render the scene (including its children) onto the screen.
  5. Register SceneManager.update in requestAnimationFrame.


This content is released under the ( MIT License.