Here is the full list of all 21 The Revenant Prince achievements.
Dying 100 times!
Finished the main story.
Defeated the watcher of darkness.
Defeated Cecil.
Found the cat village.
Left the Innerworld.
A certain penguin burning with passion!
Obtained all journal entries.
Defeated Lulu.
Met with all the joke masters.
Reached level 99.
Killed lots of people.
Cleared the Forest of Memories.
Upgraded any piece of equipment to + 10
Defeated Olga.
Defeated Bob and Carl.
Entered the Innerworld.
Defeated the Lycan.
Played for 100 hours!
Finally, it's over.
You don't play nice, do you?