I have played Xyllomer for about 10 years now, on and off.
Sadly, some of the negative sides mentioned in earlier reviews are true. BUT. Those can be found easily in any other mud I have tried. And after all, I found a civil behaviour and empathic roleplay always overcame those problems.
Much more importantly:
1. You wont encounter anyone named 'Killdude' or 'Killor' or 'R0xx0r'.
2. Xyllomer is FREE. No shareware like some other muds out there, calling it donations and then giving you exp for money.
3. No silly races like winged avians, Cat furred humanoids, reptiles, turtles, sirens, wolf-men, etc. (At least not as players! :) )
4. No random stat generation.
5. No reading through tons of bytes of help files before actually getting in on the fun.
6. No global chat. (No auctioneering players either) Just IC-crafted gemlines and guildlines. (And a newbieline)
7. Last not least, you cant do 'who killdude' and see his life-story, level, stats, achievements. If that interests you, go and ask. (Better dont ask about level and stats though.)
Ive tried some, and with all its downsides, Xyllomer is the Queen of MUDs out there.
With a rising playerbase once more, I am sure I will again spend months of my life in its realms. Its tight atmosphere and wonderfully player-developed history have drawn me in once, ten years ago, and I hope it will draw you in soon as well.