DOOM + DOOM II

If you're not using cheats then here is a quick and easy method to getting this achievement.

Doom II
Level : Map 02: Underhalls
Difficulty : I'm Too Young To Die

From the start kill the three grunts and then head through the door. Take out the two grunts and the two shotgunners and flick the switch. This will lower the wall outside.

Head through the new opening and follow the corridor around taking out the two grunts and a shotgunner.

On your left is a passageway with some armor pickups leading to a door.

Make sure you're on 100% health, go through the door and barge your way through the grunts to the super shotgun (Don't kill any!)

Once you've grabbed the super shot gun turn around and blast all the grunts.

Fingers crossed you'll hit 4 of them and nab the achievement!

To get this achievement, you must be playing anything other than DOOM and SIGIL, as those are based on the first game and, therefore, don't have the super shotgun.

I recommend you do this in Doom 2. If you're cheating, select level 3, type IDKFA and select the Super Shotgun, then play the level and you should pop it after going upstairs in the first room.

If you're not cheating, either play normally or select level 2 (The Underhalls). Play the level normally, and after you enter the "sewers" area (which is closed when you start the level), take the first exit left, going downstairs, and open the door. Clear this area to grab the Super Shotgun. Then proceed normally towards the next level. Don't worry about running out of super shotgun ammo, as there's plenty near the exit of level 2, as well as a box in the second room of level 3, by the first set of stairs you go down on.

Video guide on what I'd say is the best place to farm this achievement, as there are three consecutive chances to grab it in case the RNG is against you:

For this specific achievement, i had the hardest time.
So, go onto Doom 2 MASTER Levels, L10 - Black Tower.
As you start, on the left, see some stairs and enemies, go down, there is the super shotgun.

Go back up, then through the only doors that you can, straight infront you will see maybe 20 humans all gathered together, quickly run over, super shotgun blast their ass and hopefully you will knock 4 out at once.

Definetely the easiest way to get this. Look at 18:00 in my video if you prefer a visual :)


Achievement Timestamps:-

Intro - 0:00
1. Not So Friendly Fire - 1:30
2. An Important Looking Door - 4:20
3. A Man & A Half - 6:35
4, 5, 6 & 7. A Clean Slate, The Only Thing They Fear Is You, Hoarder & Burning Out Of Control - 7:30
8. Groovy - 8:20
9, 10 & 11. Doormat, Overkill & Heavenly Joy - 9:00
12 & 13. Alternate Dimension & More Like A Dream - 10:30
14 & 15. Cooking With Plasma & Bowling For Gibs - 12:00
16. Overprepared - 13:30
17. Timing Is Everything - 15:30
18. Skeet Shooting - 18:00
19. Untouchable - 19:45
20. Until It Is Done - 23:30
21. Shoot It Until It Dies - 25:20
22. Guns Are For Wusses - 27:10
23. DOOM - 29:40
24. DOOM II - 32:40
25. Master Levels - 35:00
26. Evilution - 37:30
27. Plutonia - 39:10
28. No Rest For The Living - 40:45
29. Sigil - 42:30
30. Kill It With Fire - 47:50
31. Screen Wipe - 50:40
32 & 33. Indiscriminate Headhunter & Legacy Of Rust - 53:30

Doom 2, load up first level on nightmare, type IDDQD (god mode) and IDKFA (all guns), switch to your super shotgun, run past the two first enemies and after the right turn, just unload your gun, you should hit more than 4 targets.

DOOM 2 in the Masters Levels, Level 10 easiest difficulty was super easy to get this achievement.

If you're not using cheats then here is a quick and easy method to getting this achievement.

Doom II
Level : Map 02: Underhalls
Difficulty : I'm Too Young To Die

From the start kill the three grunts and then head through the door. Take out the two grunts and the two shotgunners and flick the switch. This will lower the wall outside.

Head through the new opening and follow the corridor around taking out the two grunts and a shotgunner.

On your left is a passageway with some armor pickups leading to a door.

Make sure you're on 100% health, go through the door and barge your way through the grunts to the super shotgun (Don't kill any!)

Once you've grabbed the super shot gun turn around and blast all the grunts.

Fingers crossed you'll hit 4 of them and nab the achievement!