Here is the full list of all 8 The Nightmare Journey achievements.
Complete the entire nightmare journey without dying once.
Beat the game in less than 5 hours.
Assemble the puzzle in less than 3 minutes.
Defeat the Sleep Monster without dying once.
Defeat the Dumpster Monster without dying
Complete the game!
Defeat your biggest nightmare just using the machine gun.
Defeat the Alzheimer's Wizard without dying