Crossfire is a multi-player graphical arcade and adventure game made for X. It has certain flavours from other games, especially Gauntlet and the rogue-like games (Nethack, Moria, Angband, and Ragnarok). Any number of players can move around in their own window, finding and using items and battling monsters. They can choose to cooperate or compete in the same world.
libtelnet is a small library for writing telnet protocol handlers in C. It uses a fully correct state machine model and full RFC 1143 (Q Method) option negotiation. It includes optional support for MUD-specific protocol extensions such as MCCP2 and ZMP. Several test programs are included, such as the very useful telnet-proxy utility.
MV3D is a virtual world and multi-player game framework for use with Python. It was designed with scalability in mind and is able to distribute a world across as many servers as needed while dynamically balancing the load. The simulation framework is not specifically slanted towards any one genre of online game or virtual world, and can just as easily be used for a space game as a fantasy setting. Objects on an MV3D server can be simulated using the ODE physics engine for realistic interactions. A single server is able to host thousands of of simulated objects. The client works with both the Ogre3D and Panda3D renderers.
Vallheru is a turn-based, fantasy MMORPG written in PHP and MySQL (but may work with many other databases) with Smarty Template Engine, ADOdb, and PHP Mailer. It is based on Gamers-Fusion 2.5 with many modifications in security, speed, and features. It is currently available only in Polish.
JamochaMUD offers Unicode, plug-in, and multi-language support (8 different languages) to allow a more enjoyable MUCKing/MUDding experience. It features command history, synchronized window controls, experimental SOCKS 5 support, and greatly improved ANSI colour support. It plays nice on Unix systems, supports a wide range of MU*s, and also includes emulation of some TinyFugue editor controls. JamochaMUD includes classes that may be easily reused in other Java applications.
Phaos is a browser-based MMORPG. It features character creation, the ability to purchase/sell/drop potions, weapons and armor, traveling, inter-player chat, the ability to fight in the arena, explorable dungeons, an admin system, the ability to trade with other players, and the ability to fight other players. A download is available for people running Windows who do not have access to or do not want to set up a Web server.