You can make it - Open Source MMORPG Platform
Open Source MMORPG Framework
Complete Open Source and Modular solution for MMO
An open source implementation of the Ultima Online Classic Client
LSJ-Server-Terra (Java Multipurpose Sever connected with MariaDB)
A multiplatform medieval 3D MMORPG
Source of Mana is a unique 2D MMORPG
Arianne is an engine to develop multiplayer online games like Stendhal
GameServer is a sophisticated, game server designed for online games
An unmodified version of the MMORPG Impressive Title by KovuLKD
Free MMORPG
GameWhizzards is a user created, Open Source 3D MMORPG
Find the best oldschool server with the lowest ping [OSRS Live Ping]
Collection of Tools for Perfect World MMORPG
Dark Age of Camelot server emulator
World of Warcraft character converter, supporting multiple emulations
starrydb is game server engine
Python classes to work with Blizzards API
Anarchy Online Emulator
Immersive and expansive hardcore old-school 2D ORPG (MMORPG)
Blender port of Ryzom art data