I have been playing Cosrin for a couple of years now. I looked around at other MUDs but never found one that came close to Cosrin's mix of quests, fights and interaction.
Firstly, there is no PK. This means that the emphasis is on working together and not against each other. There is a thriving trade between players of spells or goods. Whether it is enchanted rings, armour, poison or pastes you get the best stuff from other players and not from killing something.
What makes Cosrin different from the other MUDs? Well, for me, it is the sense of community. Guilds have set up Mentoring systems so that new players are given advice if they wish and know where to go to get it. Most players are happy to help those in need. We have our own newspaper and a number of Clans where likeminded people can build their own smaller community.
There are a lot of staff, both hidden and in game. As well as being there to code or enforce the rules, they are primarily there to roleplay. If you need help with a roleplay such as rooms built, items created or world events, then they will help. Roleplay is the lifeblood of Cosrin.
You can come in with 5 free logins. After that the charge is $4.50/£3 per character per month. So come in, have a look around. Try out the combinations of class/race/guild and I hope to see you there.