Obviously Spoilers for the game Deadly Night. The first section will be achievements that you should naturally be able to pick up through the bad ending of the game. The second section will be achievements picked up through the good ending, and how to get it. The third section will be achievements that you may have to go out of your way to obtain, or ones with obscure titles.

Parasomnia
Have the nightmare in the motel room.

Mr Shiny
Find Mr Shiny in your bathroom after escaping his office.

That was unexpected
Be captured by the murderer as you try to run from the motel.

Broken Leg / Useless
Once completing the house level and unlocking padlock on the well, either interact without the rope for Broken Leg, or with the rope for Useless.

No Hope
Be killed by the murderer after he kills your friend in the courtyard.

In order to get the good ending, you must use the rope found in the save room at the top of the 2nd floor stairs on the nail by the door. The next time the murderer walks down the stairs he will drop the van key, which you need to pick up, and take with you when you interact with the well and jump down.

They are alive
Upon regaining control as the main character in the butcher / meat cave, the key will be on the stone table beside you. Pick it up before leaving with susan, and interact with the van to obtain this achievement.

Chicken
Die 4 times in the house level, and select the easier difficult option when prompted.

Death Addict
Die many times during the house level. I had to die 6 times.

Evidence collector
After being locked in Mr. Shiny's office, open the drawer below the VHS player, on the TV stand opposite the sofa. Pick up the VHS tape for the achievement. You will have the option of putting the tape in the player.

Explorer
Find and interact with the photograph on the floor next to the blue car in the motel car park.
Find the coin behind the motel reception. Walk around the first piles of trash, and behind it to the other, fenced off side of the building. The coin is on the floor.

Arcade Lover
To get this achievement you must complete the entire arcade game in Mr. Shiny's office, accessed using the coin in Explorer.

Stalker
After escaping Mr. Shiny's office, instead of returning to your room, immediately head down the road on foot in the direction of the sign that says services.

No memories
As the achievement says, complete the house section of the game without saving once.

Invisible
Complete the house section of the game without being spotted. Being spotted only counts if the murderer is pathfinding directly to your location, while you are free to move. So two examples where you haven't been spotted would include:

• Upon removing the pipe under the sink, the murderer will pathfind in chase mode towards the sink's location. As long as you are hiding elsewhere, you have not been spotted.
  
• When starting the house section, upon approaching the basement door for the first time the murderer will pathfind in passive mode towards whatever hiding location you are using in the basement. As long as you are using a hiding spot this does not count.

Speedrunner
Complete the game in under 1 hour and 30 minutes (in game time). This includes all the scenarios such as the 911 call.

Where is the body?
For this achievement, you will need a full playthrough. In the motel, after finding the mirror camera and heading to reception, use the phone behind the counter before entering the office. Now get the good ending by escaping with the van key, and play through the 911 call. The achievement will be obtained after completing the final cutscene.

This is my first guide so any feedback would be appreciated. Will be updating the final few achievements once I know exactly what triggers obtaining them.