Although MUDs have the potential to be amazingly fun and addictive, they are also undoubtedly the type of game with the least amount of originality.

There are many hundreds of MUD's to choose from, but there are only a few different codebases which all of them are based on. Many MUDs are just copies of hundreds of other games with a different set of rooms, and possibly different names for the skills, spells, and races. Nearly all of them use the same combat and spell systems, and many have little to no original skills or spells.

The only MUDs that are very original (Terris, Gemstone III, Dragonrealms, others) cost money to play, though they're definitely worth it for those who enjoy them.