OpenMW is an open-source open-world RPG game engine that supports playing Morrowind.

ScummVM main repository

Retro RPG Game Maker

Unreal Engine 4 Action RPG type game starter kit.

RPG Maker 2000/2003 and EasyRPG games interpreter

H2服务器引擎架构是轻量级的，与其说是引擎，个人觉得称之为平台更为合适。因为它封装的功能少之又少，但是提供了非常简洁方便的扩展机制，使得可以用C++、python、lua、js、php来开发具体的服务器功能。H2引擎的灵感来源于web服务器Apache。

An implementation of the Diablo 1 game engine

Modular game engine built with MonoGame, with GMS2-like workflow and advanced level editor

Scott's Open Source C# RPG

🎨: RPG Map Maker (Paint Tool)

Open Source role-playing game engine for Taleworlds' Mount&Blade Series written in C# using Ogre3d Engine

Old-school CRPG engine, editor and game

Script per la creazione di Giochi di Ruolo "Play by Chat" su browser

Js JRPG Engine for FGMK

A framework for making top down old-fashioned RPGs in Flutter. Currently this is based on the Flame engine.

A RPG Engine using JavaScript

Official Hamster Republic RPG Construction Engine (mirror of SVN repository)

Fantasy Grounds ruleset for "The Witcher" tabletop RPG

A tech demo for a browser-based, Pokemon-esque RPG overworld engine that even supports Internet Explorer 6.

A modern, web based, procedurally generated MUD.

The version IDMarinas Edition is based on the version 1.1.2 Dragonprime by Dragonprime Development Team (Dragonprime) and have code of Oliver Brendel (NB Core).

A library with generic and usual role playing games features.

An open source CRPG system.

Online strategy and diplomacy RPG engine

JHeroes CRPG engine and Heroes of Hawks Haven

Fun little HTML+client-side JS RPG engine

Main repository to house several examples of games using the web-rpg-framework.

Javascript Dungeon Crawler Renderer prototype

2D Game Engine written in Java

Text-based browser roleplaying game built in Unity. Currently working on significantly more updated fork https://github.com/lizard-entertainment/runityscape. Don't fork this one!