Well, Walter's company is Digital Mars so that's where he gets his naming scheme from. Nothing to do with Doom except they both are using the same Greco-Roman deity astronomical naming scheme.
Originally D was supposed to be named Mars. The stdlib is named Phobos and there is a project called Deimos which is about providing bindings to C libraries.
Excerpt from the link above, that says what the post is about:
"Here are a handful of D programs that use various features of the language and some of its libraries, on my blog. Most of them are simple command-line utilities to do various things. Readers may find them of use to get a flavor of the language and to know some of the kinds of things it can be used for."