Download MS-DOS version 1.1 (690 K)
I don't know the minimum speed your processor needs to be but I'd imagine you'll need at least a Pentium II. You'll also need at least a 16-bit video card, plus a soundcard for sound. A few people cannot get this working despite seeming to have the necessary equipment - I'm sorry about that. See the file README.TXT for help.
You'll need to unzip this file, using a program such as WinZip. Then run the file UHOH.EXE. Then let the strangeness commence...