My 16-17 year old self has spent more time playing Chaos Strikes Back on Atari ST than my 32-year old self dares to admit.
Turns out, there's a whole fan subculture for Dungeon Master and Chaos Strikes Back out there. There's The Dungeon Master & Chaos Strikes Back Encyclopaedia with information about games as well as a download section with several reincarnations of the games.
Most notable among them is one by one Paul R. Stevens who created an exact replication of the game. Here's how he did it, in his own words found here:
Finally, after many years, I got my hands on the binary executable for the game. I wrote a disassembler to turn it into human-readable op-codes and proceeded to translate it to C++ using the Microsoft Version 6.0 C++ compiler. Eight hours a day for six months. About 120,000 lines of pseudo-assembly language. Crazy thing to do. But it works.
Just insane. Clearly, one of the highest examples of computer nerdiness I've ever came across. Hat off. The biggest achievement is that the resulting code is fairly cross-platform; there are distributions for Windows, Linux, and Mac OS X. And I can certify, the gameplay feeling is identical to that you get from playing it on an original Atari ST. Well, except it loads much faster. And the pixels look blockier on these damned modern high-res displays than they did on a TV screen back in the day. And the Mac OS X port for some reason doesn't deal well with keymaps, so you lose the ability to strafe from the keyboard, which can make the game tedious at times. The Windows version fares better in this regard, and you can even assign mouse clicks on a particular screen coordinate to keys on the keyboard. As anyone who played these games in original will attest, this is an invaluable feature to have as it is much faster to hit 6,4,4,spacebar than to click on four icons on the screen to cast a fireball :-)
Then there's Dungeon Master Java by Alan Berfield, an also cross-platform version of Dungeon Master engine written in Java, with custom raytraced art, giving the game a bit more polished feel.
And then if you look a bit more around on the net with a search engine, you can also find an incredible ammount of custom-designed dungeons fans are creating.
Jeez, now if only I again had as much time as I had 16 years ago...