This is a complete storyline walkthrough guide which contains spoilers. You will need to play on the latest German Build to unlock all achievements (credits go to Gunner for finding the solution

Head out of the room and up the hallway towards Jan’s office
Request access to A38 and scan your ID card into the machine
Leave the room and proceed to the elevator on your right

Head into the portal room
Enter the first portal
Run 2 laps

Pickup a rock (LMB)
RMB to throw. Note: press RMB with the cursor directly onto the bottle to hit it

• Achievement: Precision (100% accuracy).If you miss, alt f4

Leave through the portal
Exit the room
Head left then down the hallway
Talk to the man at the gun store to obtain a hint system: Note the hint system can be used at anytime incurring no penalties
Behind you, equip the green costume. Interact with all the other costumes on display

• Achievement: Costume Party

Return to the portal room and pull the lever
Pickup the mission disc and insert into the machine on the right
Code is 1234
Enter the portal

Kill the duck at the start of this mission:

• Achievement: Bug free

Head right
Enter the tavern. Immediately approach the bartender and request to buy the drink "Holy Brew"
Tell the bartender you don't have enough money to buy the drink

• Achievement: Priorities

Speak with the person standing in front of the fireplace to distract the bartender
Go behind the counter and steal a beer
Exit the building
Head towards the top exit into the main city
The jail is located in the building with the noticeboard at the front of the building and an advertisement for enlistment
Speak with Bagdan (in the cell)
You will get access to the house with a blue roof
Join the queue
Press the button on the enlistment counter to join. You will receive a hamster
Head over to the information counter and spam the bell

• Achievement: Annoying customer

Exit the building and speak with the fortune teller

• Select “Yes please, I hate surprises”
  
• Speak with the fortune teller again to earn achievement: The future

Head to the marketplace
Interact with the vendor (top middle) to receive a hammer
Speak with the fruit vendor (bottom left) to receive a free tomato
Throw the tomato at Henry Jr (the character walking around the marketplace, dressed in white tophat, shirt and black pants)

• Make sure the character is out of view for a long distance shot
  
• Achievement: Sniper. If you miss, collect another tomato

Head to the graveyard and enter the crypt
Use the hammer on the coffin
Speak with Sir Henry (exhaust all dialogues)
Pickup the “I am rich” card inside the coffin

Return to the marketplace and speak with the topleft vendor.
Leave the city and head into the bar
Speak with the bartender to receive a sidequest to get rid of the rat outside
Go to the farm on the right
Pickup a shovel from the haystack
Interact with Farmer Joe and select all options
Turn the machine off and place the hamster in
Chase the cat around the city
Use the card to enter the north exit of city
The cat will remove the rat (pickup a barrel)
Speak with the bartender to receive a drink coupon
Trade-in the coupon with the vendor in the marketplace for a book
Return to Sir Henry in the crypt
Pour the beer in the coffin
Collect the outfit outside the enlistment building on the clothesline (top right of city)
Drop the clothing item in the coffin
Use the shovel on the graveyard for a key
Unlock Bogdan’s house (the one with a blue roof)
Collect toilet paper and bread from the table
Use the bread to lure the chicken back to Farmer Joe (the chicken is located in the garden)
Place the barrel under the machine and craft a brown slurry
Pour the slurry in the coffin at the graveyard
Head back to the house and sleep

Head to the crypt
Speak with Francois (he is located in a portable toilet between 2 houses)
Handover the toilet paper for a key to the museum
Unlock the museum
Collect the jar and leave the building (do not walk forward any further)
Collect 3 fireflies
Clothesline, graveyard, vegetable garden
Enter the museum

• Achievement: save the vases

Collect another jar
Tip over one of the fire basins to burn the mummy
Place the remains in the jar
Enter the next room, pickup the red crystal and replace with the jar
Return to the crypt and give Sir Henry the soulstone
Speak with Sir Henry (exhaust all dialogues) and head outside

Storyline Complete

• Achievement: The end