Exactly which song "At Doom's Gate" is based on has been disputed, because this style of riff was hugely popular in 1980s heavy metal. It is mostly agreed that the chorus riff of Metallica's "No Remorse" was the song Prince was trying to emulate. However the riff, almost verbatim, is also featured in D.R.I.'s "Hooked" from their 1987 LP Crossover, while Metallica's "Master of Puppets" has a similar riff and is also suggested. A similar sequence is heard in "The Family Ghost" by King Diamond (the approximately 2:05 into the song). Slayer's "Behind The Crooked Cross" at 1:08, Blackmayne's "Twilight Of Lear" from their 1985 LP Blackmayne, Aria's "Это Pок" (English: "This Is Doom" or "This Is Fate") from their 1985 debut album Мания Величия (English: Megalomania) are also possible, as well as Bathory's"Necromansy". Also similar riff can be heard in Yngwie Malmsteen's "Caught in the Middle", Judas Priest's "Painkiller" at the beginning, Grave Digger's "Get Away" and Warlock's "Metal Racer" at 1:54.
The Doom IWAD file includes two title screen MIDI lumps, d_intro and d_introa. The latter is used when using OPL MIDI playback (ie. on an Adlib or Soundblaster card).