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.
Slash'EM (Super Lotsa Added Stuff Hack -- Extended Magic) is a variant of the hugely popular roguelike game NetHack. It adds more monsters, more objects, more dungeon levels, more roles, and more races, shopkeeper services, and techniques for you to use, and invisible objects and gypsies for those who feel lucky. It also comes with a GTK windowing interface and higher resolution tile sets as options.
SMM++ Mud Client is a mud client with extended and unique features. Aside from all standard mud client functionality like ANSI color support, aliases, action triggers, and tab-completion, SMM++ features a highly-customizable user interface (labels, buttons, and menus) and unique and powerful mapping capabilities, and SMM++ is the only mapping crossplatform (Tcl/Tk based) mud client available.