Serious Sam 4

This is a Side Quest found during the mission "The Package". Shortly after you are outside and cross the small bridge into the next door, keep going to the right until you find a computer terminal with a blue highlight around it. Interact with it and choose these options:

• A break sounds good
• To the Prancing Kleer!
• any drink, it doesn't matter which you choose
• WHAT?!
• Talk to Hellflame and Rodrigor, the order doesn't matter
• Leave
• Go through Grunwald
• Offer to take off your shoes
• To the Castle!
• Speak to Baron Brandus
• Tell him about the beer shortage
• Accept quest
• Speak to Zadok
• Ask what happened to beer
• Head for Wizard's Keep
• Ask about the beer draught
• Ask about the way to Zythos Mountains
• Set out for Zythos Mountains
• Take the road that crosses Faerie Forest
• Tell them about your quest
• Continue your journey
• Ask about Quinnriel
• To the mountains!
• Approach the cork
• Hellflame
• Victory
• Quit

After the game is done, turn to the highlighted switch to your left to unlock the achievement.

This is a side mission on the mission called "The package" what I did was follow this video guide for the answers and the location. Achievement will pop upon opening the door after doing the text puzzle.
All credit goes to the YouTuber Top Gaming With Zameda1