I never played a DOS game before.....Is it sorta like QBasic? I played some of those games...
If you're using Windows XP:
and hit enter.
That's DOS. It's an operating system like Windows, only without a GUI but a command line prompt.
Try it, use cd.. to exit a directory, cd "directory" to open it, and tiype the filename to open an executable. Whatever you do, don't type "format c"