Edit: Keep in mind that I made this guide in 2021, if something changes in game you can let me know politely. Thanks!

I didn't discover these on my own, I had a youtube video help me get the achievements that I will share with you here. Watch the video to make it easier for yourself if you're having problems.

RVNH3CT1CD3M0??? - Locate the secret level 'Hectic'

• Shoot all barrels (10 in total). Don't shoot the first one you see, leave it for last.

Secret Sleuth - Discover a secret area

• Some barrels are in secret areas behind walls and such, the video will help you find them.

Password: YWW4 7HVD BCLG RKVB

Rip and Tear! - Kill a Cyberdemon
Escape Artist - Finish 'No Escape' on Watch Me Die skill level

• Save a lot to make it easier for yourself, because it's kinda hard...

Password: W83M 7H20 BDY0 N9VB

Unholy Firepower - Find the Unmaker
My Cause is Just, My Will is Strong - Find the BFG9000
Mother May I? - Defeat the Mother of All Demons on The Absolution

• Easy level, just close the doors fast so you don't have the room flooded with enemies.

Password: V87L 7C28 BDT1 59VB

Persistence is the Key - Acquire all 3 Demon Key Artifacts in the main campaign

• You will have 2 demon keys already at the start, you just need to get the one left on the level.
  
• To see how to drop the platform that has the demon key check out the video.

Password: ?QDM 7HYC BB4X FJVB


Enter the password and press escape, after that click on Features.


Press the arrows on your keyboard till you reach either Warp To Fun: Cat And Mouse or Warp To Lost: Final Judgement.

You should see this:


The password alone will not put you on the levels if you do not enter the Features after you load in...

Thank you for reading my guide, it's very much appreciated.
Bye now!