I have been using internet chats since the 1990's and platforms like IRC, Activeworlds, and for the last few years Opensim (opensource version of Second Life). Mixed in there were MMORPG's like Everquest and World of Warcraft for good measure. Ive just recently come across a platform that is like a mixture of both types called Worldforge.
Worldforge is not new - it has been around over a decade but the pace of development seems to have picked up in the last few years. There are clients for the main three platforms: Linux/Mac/Win and the server can be run locally as well to make development easier.
I would say that Worldforge is similar to Opensim in terms of letting you edit the world in the client, but it has a RPG element to it and has less features than Opensim. Opensim on the other hand is lacking a native RPG element but has the LSL scripting language.
Support for Worldforge is primarily on the email list and IRC on a private server. Ive found the email list quite useful and there is a archive for it as well.
Worldforge is intended as a general MMO gaming engine and has two example datasets, "deeds" and "Mason" which you can load and run in your server. Mason is a improved version of the game "Acorn" where you raise pigs and sell them. The goal for Mason was to try to implement a crafting based world with emergent gameplay, the goal for Deeds is to instead focus on a more curated environment where a world builder creates a story for players to experience. Mason isn't actively being developed.
Im working on a reduced scale MMORPG called TinyRPG which is to be a subset of my previous project "Mundo Sangre", and you can find out more about it and Worldforge at my website http://TinyRPGGame.com to follow along with the progress of the game.
If you are at all interested in any of these topics please go to http://Worldforge.org and have a look around!
An Introduction to Worldforge
