Gather 'round and hear the tale of Doomguy.
Ah, Doom. The timeless story of a boy (or girl) becoming a man (or manly woman) through trial, hardship and piles of dead monsters. Now, let us recall this ancient tale from 1993 that teaches us if you aren't
in America on Earth, you might as well be in Hell.
So, you are part of an elite military rapid response squad, or Space Marines. The Martian moons of Phobos and Deimos are under attack from some alien menace after an experiment gone awry. You report for duty. You're ready to serve, ready to fight. You're ready to be...the doorman.
Anyway...you're at your post. Inside you hear gunfire, screams, splatters and roars. Whimpering, praying and explosions. Bewildered, you think:
"Well I hope everyone's alright in there..."
After a while things die down. You decide to make sure everything went ok. You expect it didn't when you spot half-a-dead Bill with a chaingun clutched in his hand.
You look up and see zombies, imps and demons. All your comrades are dead and your shuttle is right behind you. Naturally, you decide to kill everything and avenge your comrades, since escape is impossible...except for the aforementioned shuttle.
So, pistol in hand, you kill a bunch of shit. Zombie hordes? Explosive barrels. Imps? Shotgun. Demon pig monsters? More shotgun, because seriously that thing kills everything. Eventually these monsters start turning invisible just to hide from you, but you've got the eagle eyes and the empathy of a rock, so you kill them anyway. You kill so much shit you literally breach Hell itself, then kill more shit.
Then you find Hell's secret stash (drugs, not porn) and get the energy to slap the shit out of Hell's champion, the Cyberdemon, until Hell literally opens a door to Earth for you to leave. Presumably right in front of your house too, lest you have a reason to come back.
So welcome home. But why is your dog looking so drawn and quartered?
They decided to take Earth.
Now some would wonder why the demons of Hell would place the one person they wanted to avoid on the piece of real estate they want to claim. You just wonder why your dog won't play fetch anymore. Then you come to a conclusion. They will pay for killing your dog! And Earth, I guess. But mostly your dog!
So you take a stroll and kill a few hundred monsters before meeting up with Earth's last survivors, who are re-enacting Saigon at Earth's last spaceport. You decide to join them because, hey, last man on Earth, right? Unfortunately, someone has to stay behind and open the gates for the rest of mankind to escape. Why they don't have a remote garage door system is anyone's guess. In what is possibly a lapse in judgment, you volunteer.
So humanity escapes, leaving you alone with hundreds of thousands of monsters, squared. You sigh, thinking of what to do with your life. Better keep those ambitions in check though. No point writing a best-seller if no one's around to read it. Yep, better keep those goals small--
"Well, might as well take back Earth!"
Really? Well, yeah, because that's exactly what you do, single-handedly reclaiming the planet. You kill so much shit the second-to-last demons sprint to their portals and immediately seal them behind them, witnessing you do unspeakable things to the ones too slow to reach them.
Remember Starship Troopers when they were fleeing that camp and got ripped apart? Yeah that was nothing.
Remember Independence Day when those people got heat blasted by that obvious giant alien death cannon? Small potatoes.
Remember the Doom movie, when Karl Urban threw that grenade through the portal and killed the Rock-monster? Yeah, those demons were wishing you did that after what they saw.
They also were wishing that they never saw the Doom movie.
Congratulations, you took back Earth! Repopulation time!
Years have passed. You are now the commander of a new base on Mars. The forces of hell desperately want to feed their "killing humanity" fix.
The stage is set, but Hell has learned its lesson.
DON'T FUCK WITH DOOMGUY!
So they hatch a plan. The portals won't work. You'll be waiting wherever they open up with a smile and a chainsaw. So they build a giant spaceship--from Hell!-- and fly it across space, the long way around, just to avoid you. They reach Mars, but don't attack.
After all, they're not that stupid.
They wait for you to go for a walk.
While you're gone, they proceed to murder the shit out of everything under your command. They even take care of your pest problem. But their worst nightmare comes true: you get back before they are finished.
So, pistol in hand once again, you walk toward the giant scary Hellship and kill an assload of Hellspawn. They don't even try to fight this time. They drop everything and run the fuck away because, FUCK, Doomguy got home early!
It's no use though; they're helpless as you run them over with death, undoubtedly bear hugging the last few Hellknights so they can't escape on the ship or through a portal to safety. No one reaches safety.
Your people are avenged and Hell literally has no more shit to sneak in behind your back.
But, damn, you hope all the hippies are dead. The last thing you need is to come home and have one spit on you for doing your job well.
Don't worry, Hell hasn't attacked again. This is simply a retelling of your first time schooling monsters. It's a biopic on your life, severely toned down to be more believeable to the audience...so yeah, you are basically the sci-fi space version of Audie Murphy.
And id has announced Doom 4. Perhaps Doomguy bitch-slaps monsters from his Hover-round?