Here is the full list of all 41 -KLAUS- achievements.
Earn all the achievements.
Get a memory door piece.
K1 joins to the journey.
Make 1000 Jumps.
Solve the first puzzle.
Make 5000 jumps.
Finish the clon section of the office floor without dying.
Finish the chapter 5 of The Electric Floor without dying.
Throw Klaus with K1 for the first time!.
Finish the K1 flight of K1 on Chapter 2 of the Ducts Floor.
Finish the Chapter 4 of the Ducts Floor.
Finish Chapter 4 of The Basement Floor.
Destroy 25 Mug workers.
Destroy 50 Objects With Uppercuts.
Get the hidden portal of the Chapter 5 in the World 3.
Finish a puzzle without destroying the Key.
Make 10000 Jumps.
Destroy 4 objects in a row without touching the floor.
Hack 100 CPUs.
Is that K1?
Finish chapter 5 of the Ducts Floor without dying.
Finish the K1 flight of K1 on Chapter 6 of the Electric Floor.
Smash 20 clones with K1.
Beat any world without dying.
Beat all the records of all the Chapters.
Beat The Basement Floor.
Beat The Ducts Floor.
Beat The Office Floor.
Beat The Electric Floor.
Beat The Glitch Floor.
Get the first Ending.
Unlock the Arcade Mode.
Relive the 1st Memory.
Relive the 2nd Memory.
Relive the 3rd Memory.
Relive the 4th Memory.
Relive the 5th Memory.
Relive the 6th Memory.
Do everything.
Beat Mecha Klaus.
Collect all the memories.