If you spent a fair bit of December 1993 onward blasting hellspawn, you might know a thing or two about Doom and its sequels. Like demonic armies, there’s a lot more to the iconic first-person shooter than meets the eye.

1. THE NAME DOOM CAME FROM A TOM CRUISE QUOTE.

Programmer John Carmack said in an interview with the site Doomworld that the game’s title was inspired by a scene in The Color of Money in which Cruise’s character pulls out his custom cue case at a pool hall. Carmack reminisced about the scene: “‘What do you have in there?’ asks someone. ‘Doom,’ replied Cruise with a cocky grin. That, and the resulting carnage, was how I viewed us springing the game on the industry.”

Other names were discussed before the final one took hold. The game was almost called “Attack of the Attackers,” but the id Software team decided this title was “too silly.”

2. DOOM WAS CONCEIVED AS ALIENS MEETS EVIL DEAD II.

In the same interview, Carmack revealed that the game’s producers saw it as a hybrid of James Cameron's science fiction staple and Sam Raimi’s over-the-top cult horror classic—which sees characters accidentally summon and then brutally battle undead terrors. The design team even included chainsaws and shotguns, favorites of Evil Dead’s Ash, among the game’s weapons.

3. THE REVOLUTIONARY SHOOTER CAME FROM A TINY PRODUCTION TEAM.

Enormous studio crews put together many of today’s top games, but only 15 names feature in Doom’s credits. At the helm were John Carmack, who carried most of the programming duties, John Romero, who handled level design, and Tom Hall, whose elaborate Doom Bible gave the game creative direction and a detailed world (though much of it never made it into gameplay).

4. GAME DEVELOPERS USED MODELS TO DESIGN AND ANIMATE CHARACTERS.

After they developed figure sketches, Adrian Carmack (no relation to John) and other game artists built sculptures of the Doomguy, Arch-vile, Mancubus, Revenant, Spiderdemon, Baron of Hell, and Cyberdemon characters. Designers then used a video camera to capture the models from different angles. Finally, they scanned the images and animated, rescaled, and recolored them in John Carmack’s revolutionary Doom engine.

5. DOOM’S ICONIC MUSIC HAD METAL INFLUENCES.

Composed by Bobby Prince, the soundtracks for the first two Doom games were inspired by such bands as Slayer, Metallica, Megadeth, Pantera, AC/DC, Alice in Chains, and Black Sabbath. Many Doom tracks mirror metal and hard rock hits so closely that fans have paired them up for easy comparison:

6. THE GAME’S LEVELS ALSO PAY TRIBUTE TO THE ERA’S BANDS.

The musical influences aren’t limited to the music. Over the years, several Doom levels have shared names with popular bands (though creators won’t reveal which were deliberate nods), including House of Pain, the Living End, Nirvana, Genesis, Skinny Puppy, and Slayer.

7. METAL AND ROCK BANDS RETURNED THE FAVOR.

The Smashing Pumpkins, Warbringer, Hexen, and many other metal and industrial bands have included tributes to Doom in their songs. In 1995, Nazareth guitarist Manny Charlton even sent Romero a tape containing an untitled song for shareware-style distribution with a note reading, "For all the guys and gals at I.D. who came up with the coolest game this side of hell, kick some demon butt to this!"

8. DOOM’S SOUND EFFECTS HAVE HAD A LIFE OF THEIR OWN.

In addition to onscreen shout-outs in Friends, The Simpsons, Family Guy, Mystery Science Theater 3000, E.R., Stargate SG-1, and Doctor Who, traces of Doom have been spotted in a wide range of TV shows and movies thanks to a popular sound effects gallery that provided many of the game’s noises. The sound made by Doom‘s doors has been used over and over, while the howl made by dying Imps—often compared to that of a sick camel—can be traced to 1962’s Lawrence of Arabia, which did indeed feature lots of exhausted camels.

9. BEFORE FIRST-PERSON SHOOTERS, THERE WERE “DOOM CLONES.”

Many credit Doom as being the first proper first-person shooter and one of the most influential, at least, having built upon play and layout styles from id Software’s previous hit, Wolfenstein 3D. After Doom’s release, similar games (many copying various Doom elements) were simply referred to as “Doom clones” until games like Half Life, Duke Nukem 3D, Halo, and Goldeneye 007 expanded the genre with new elements in the late ‘90s.

10. DOOMGUY HAD NO REAL NAME UNTIL 1995.

The muscular marine piloted by classic Doom players has little characterization and no name because, John Romero explained, this helped make the first-person sci-fi/horror more immersive. With the release of Knee-Deep in the Dead, the first Doom series novel, the protagonist gained the name of Flynn "Fly" Taggart.

11. DOOM WAS ORIGINALLY FREE.

The original Doom consists of three multi-stage episodes. The first, “Knee-Deep in the Dead,” was available as a free shareware download. Players who wanted the remaining two episodes had to drop $40 to buy them from id Software.

12. IT WAS A HIT RIGHT OUT OF THE GATE.

The price was right, and players quickly fell in love with Doom. A 1994 Washington Post story reported, “Literally within minutes of its release in December 1993, Doom was establishing its legend by causing a massive logjam on the computer network at Carnegie Mellon University.”

Carnegie Mellon wasn’t alone. A December 1993 Houston Chronicle story reported that Doom “was so popular that college students booting it up in multiplayer mode trashed the networks at two universities.”

13. EVEN ID SOFTWARE SAW IT AS A PRODUCTIVITY DRAIN.

College students weren’t the only ardent fans—the bored-at-work crowd fell in love with Doom as a time waster. The aforementioned Washington Post piece revealed that even id Software wasn’t immune to this violent procrastinating. Jay Wilbur, id’s CEO, told the paper, "We had to have conversations with some of our people. Projects weren't getting done."

14. ITS RELEASE COINCIDED WITH U.S. CRACKDOWN ON GAMES WITH ADULT THEMES.

The relatively brief history of videogames includes a number of public and legal controversies, including the joint Senate Judiciary and Government Affairs Committee hearing on video game violence held the day before Doom’s December 10, 1993 release. Soon after, the self-regulating Entertainment Software Rating Board (ESRB) was established to assign ratings to videogames, and Doom—which upped the level of violence (and especially gore) from predecessors like Mortal Kombat—has since borne a “Mature” rating.