Click on the links below to download MOSLO, a program which you use to run old, slow DOS programs on modern, fast computers.  There are three files:  MOSLO.COM, MOSLO.EXE and the editable batch file MOSLO.BAT which you will customize so it references the program you want to slow down.

Example:
You have an old DOS program in the directory C:\GAMES\OLDGAME
The executable is called C:\GAMES\OLDGAME\Runfile.exe.
You want to slow it down 20%.

1.  Copy MOSLO.BAT, MOSLO.COM and MOSLO.EXE into the directory C:\GAMES\OLDGAME
2.  Use Notepad to edit C:\GAMES\OLDGAME\Moslo.bat 
3.  Have the line read 
       moslo.com /20 runfile.exe
4.  Save the file and exit from Notepad.
5.  In Windows, instead of having your start menu point to Runfile.exe, have it point to Moslo.bat
If the program still won't run, slow it down more.  

Download the files here