The creator of 'Dungeon Master', Ginseng, is apparently still active in the BYOND community, but is working on some other game on the service, Lands of Legend. I tried it out and wasn't impressed, it comes across as a graphical MUD / Rogue-like / Diablo with a bewilderingly obtuse interface. You can still build walls and such, apparently, but it doesn't seem to be the point.
It's really quite sad that the last available version of Dungeon Master was released last year because of this, since it actually offers gameplay that isn't easy to find elsewhere. Apparently it's actually buggier than older versions. Really goes to show how lucky we are that Toady's so commited to DF, when he releases a new version that's got crucial bugs in it it's usually fixed within 48 hours, but if you like Dungeon Master you've been waiting 10 months to have the server not crash every couple hours.
DM isn't really an online Dwarf Fortress, it's really more like a fast-paced Wurm Online that gives you the option of directly controlling multiple units. It dutifully clones a lot of the options that DF gives you, except the vast majority doesn't matter. DM also has some significant failings that make it tedious. There's no real automation for your units, so if you want to cut up and cook 9 fish, you're looking at dozens of double-clicks and a few single-clicks (it's an important distinction, click twice on the fish in inventory and it will be dropped before you choose what to do with it, meaning you can't do anything with it and it just lays there). Path-finding is very weak.
Not having to manually carry every single stone, log, and chunk of ore in Dwarf Fortress, makes up for ANY issues one may have with not having direct control over dwarves. It's certainly made me aware how lucky I am that all I have to do is some tedious job-selection now and then.
The multiplayer is what saves Dungeon Master and makes it, from what I can tell, the only worthwhile game on the entire BYOND network. I fooled around a little with a clumsy little dwarf fort until I was recruited by the cult of Jebus and so my six dwarves ran over hill and dale (occasionally falling down and breaking their legs) with some comrades searching for converts, and invading a goblin colony and killing a bunch of them. We ran off when all the orcs roze up as zombies, then started a new fort to defend from an aggressive and powerful foe. Then the server crashed. I started again about a half hour later when the server became available again, staying solo this time and making a tidy little fort, building up my population to a respectable 8 dwarves and working on raising the skill of my metalcrafter so we could get great weapons and armor. Then it crashed and it still hasn't come back hours later.
About 90% of the active games on BYOND are DBZ and Naruto themed, so I guess it fills a necessary niche for teenagers and otakus, but gameplay-wise it really seems useless without a DM server .. and DungeonMaster actually being stable, which it evidently isn't. There were also some 'murder mystery'-esque games, interesting idea but those already exist elsewhere so I don't see the point even if they do mix things up by being set on spacestations and the like, and the interface of the one I tried was the most obtuse yet.
(edit) I just read that a new guy got the source for D.M. on July 16th and is apparently working to fix the bugs, so that gives me at least some dim hope. I'm certainly not going to ditch DF, but as a change of pace, basically a different game altogether, DM's kind of neat and I hope it gets better.