gasti-jm/argentum-online-lwjgl3
MMORPG Video Game of the year 1999 created in Visual Basic 6.0 by Pablo Marquez (Morgolock), this game is open source. I have translated it to Java with LWJGL3, this game would be the base client, the connection to the server is being implemented with Java sockets.
GitHub repository with 15 stars and 6 forks.
Language: Java