Multi-User Dimensions, also known as MUDs or Multi-User Dungeons, are a somewhat generalized category of roleplaying games that can be either graphical or text-based in nature.
Graphical MUDs Edit
Graphical MUDs are often written in either Java or a lower-level programming language such as C++, Python, or C. They often require specific programs, such as the game client itself, to be installed on the players' computers. This can create issues if the game client is incompatible with certain popular operating systems, such as Macintosh or Unix.
Browser-Based Graphical MUDs Edit
These, also known as web-based MUDs, are played through a web browser, such as Firefox, Safari, or Internet Explorer. They may require the Java or Flash browser plugins, but many other games in this category can be played with any modern browser, without problems.