Here is the full list of all 34 Demonheart achievements.
Max out both Good and Tactful points.
Max out both Evil and Tactful points.
Max out both Good and Defiant points.
Max out both Evil and Defiant points.
Finish Chapter 1.
Decipher all the messages in Chapter 1.
Read the book about demonspawn in Chapter 1.
Examine Mr. Edgardo after the dinner with Orchid.
Molest the demonspawn.
Decipher the message in Chapter 2.
Kill Mark.
Finish Chapter 2.
Decipher all the messages in Chapter 3.
Ask the demonspawn as many questions as you can.
Kiss Sir Brash.
Finish Chapter 3.
Decipher the message in Chapter 4.
Read all the entries of Rivera's journal.
Finish Chapter 4.
Finish the game as Good Bright and as Evil Bright.
Finish Chapter 5.
Decipher the whole message in Chapter 5.
Kiss Ari.