AweMUD is a MUD server for use with fantasy-settings. Features include fully dynamic objects and characters, an advanced scripting system, and custom worlds. The engine will eventually have completely interactive rooms (items can be placed under benches, doors can be destroyed), complex magick, and interactive NPCs.
Mason is a game system being developed by WorldForge. The primary focus for Mason is to enable players to build a persistent world in-game. Players will be able to manipulate items by creating new items from raw materials, attaching existing items together, or splitting items into component parts. Complicated structures such as houses can be designed on paper as a blueprint and then built with suitable building blocks and skills.
Battletech MUX is an Internet based, real-time rendition of the popular Battletech board game. Players take to the front lines in their very own mechs, tanks, and similar implements of destruction. Featuring an internal scripting language called SoftCode, game admins may sculpt their sites into whatever they can imagine, be it small-scale combat or massive, galactic conflict.
ErisMUD is a MUD/MOO server/engine written in Python and supports many features: rooms, NPCs, items, player skills and stats, ANSI colors, a help system, damage/healing, etc. SQLite is used to store the data, so no files are required for building (unlike LPMUDs). Short and easy internal commands take care of the development and maintenance.