You'll need a jailbroken device as apple pulled iDos from the app store. In cydia, add this repo: http://www.litchie.net/cydia
Download it, and off you go! I edited the config and added the line cycles=4000 in the [CPU] section, which I think may have helped with the stuttery music on the door screen. I only tried it for like, 30 seconds, but movement seems fluid and I am sure it would work more without any issues.
By default, the controls are pretty bad, however I suspect some config hacking to rebind keys to the numpad to allow quick movement via say, WASD would make it just about playable... and if you can bind keys to mouse click at x,y on the screen it would make combat possible, both through attacking (say, ZXCV for each weapon, 5TGB for each attack type) and spells, maybe 12345 a la DM2.. just speculating though as I haven't played with it yet. The way the mouse works by default (dunno if you can change it) is rather annoying, I sometimes double click by accident. Anyway, it's worth checking out. DM2 might run as well, I imagine it's system requirements are higher (25Mhz 386 DX is min spec apparently).
To install, just download DM for dos, pop the folder into /var/mobile/Documents/ on the phone, and launch dosbox. Switch from C:\ to D:\ (they should be both pointing to the same place) and run install, and install it to c:\ (the installer doesnt let you install to the same drive for god knows what reason). then just type dm and press enter
I remember almost ten years ago (christ!) posting how to run DM in DosBox on the PC, now I get to tell you how to run it on iPhone, so cool
