Here is my 100% Achievement guide for Glass Masquerade 2!
Open up a level but BEFORE you do anything.. have a look in the bottom right corner where it says "Difficulty", just press that once and the green symbol changes to red.. This signifies that it's now on hard mode which you need to get 100% in this game!
It's as simple as that, complete every level on hard mode, another 1000GS added to your overall score.
I've done a picture only solution as I find it's easier to compare with what piece you have rather than trying to follow a video.
Hope this helps and you enjoy!
Timestamps for each level:-
Level 1 - All Around You - 0:48
Level 2 - Paralogic - 0:58
Level 3 - Playing Pretend - 1:09
Level 4 - About-Face - 1:19
Level 5 - Excerises In Negation - 1:29
Level 6 - A Road Without End - 1:39
Level 7 - Tunnel Epiphany - 1:50
Level 8 - Indirectly Direct - 2:11
Level 9 - The Combination Theory of Addition - 2:32
Level 10 - The Knowledge of the Many - 2:52
Level 11 - Trapped in Amber - 3:12
Level 12 - A Rule to the Exception - 3:32
Level 13 - The One Who Laughs - 3:52
Level 14 - The Pendulum of the Scale - 4:12
Level 15 - A Strangers Account - 4:32
Level 16 - Shouldering The Craft - 4:52
Level 17 - Etched Gold - 5:12
Level 18 - A Theater Of One - 5:32
Level 19 - A Knockout Tournament - 5:52
Level 20 - Nothingham - 6:12
Level 21 - An Other - 6:32
Level 22 - The Finest of all Foes - 6:52
Level 23 - About Your Sorrow - 7:12
Level 24 - A Crooked Mile - 7:32
Level 25 - Black, White, Red - 7:52
Level 26 - An Interest of Conflicts - 8:12
Level 27 - They Who Are Those - 8:32
Level 28 - Encapsulation - 8:52
Level 29 - Eternal Notes - 9:12
Level 30 - Miracle Monster Monstrosity - 9:32
Level 31 - Tatters and Shards - 9:52