Alrighty, so I figured I'd make a guide thingy for anyone who wants to unlock all the endings and CGs :3 For the most part, it's pretty easy! It's just one of the endings requires you to do something quite specific to get it.

Please note, since this is a guide to unlocking everything, there will inevitably be spoilers here, so if you don't want spoilers for any parts of the game you've not yet seen, don't read ahead! I'll try to keep the CGs section as spoiler-free as possible for anyone who wants to try and unlock all of those without being told everything that's going on in the story, but the endings guide will have full-on spoilers.

- CGs - 

CG 01: [Melancholy Mannequins]

Has 2 versions which will both unlock automatically as you progress through the story.

CG 02: [Watch Your Step]

Is unlocked while playing as Morgen when she's in her black dress. There are two ways to get it. When Morgen hears the scream, choose the option to follow the sound, and then choose to go right OR simply choose to explore elsewhere instead of following the sound.

CG 03: [Bloodbath]

Is also unlocked when playing as Morgen in her black dress. When the choice appears to take the pills or not, refuse to take the pills. You will then end up reaching the scene with this CG.

CG 04: [May I Have This Dance?]

This CG is unlocked when playing as Morgen in her red dress, and is pretty easy to get. When asked to dance, select yes to take his hand rather than the option to suggest going outside.

CG 05: [Lugen!]

This is one of several CGs that is unlocked during the scene where Morgen can read various notes and diary entries. You need to click on the small book that is by the upended chair near the middle of the room. This will trigger a scene that unlocks both [Lugen!] and then afterwards also CG 06 [Schrat's Spell]

CG 06: [Schrat's Spell]

See above, as it's unlocked via the same method as CG 05.

CG 07: [Craft Her A Vessel]

This is another of the CGs that is unlocked in the room with all the notes to read. You need to click on the pile of books on the table at the right side of the room.

CG 08: [Kiss The Cook]

This is the last of the CGs to be unlocked in the reading room. For this one, you need to click on the pile of books on the table at the left side of the room. These books will be missing from the screen if you are playing at certain resolutions. You should be able to always click them in 16:9 and 16:10.

CG 09: [Heirate Mich (Versions A & B)]

These CGs are unlocked automatically as you progress through the story and share the same slot in the gallery.

CG 10: [When One Form Fades, With Haste, Devour]

This CG is unlocked automatically as you progress through the story.

CG 11 (A & B): [Jilted & Hitched]

These CGs are unlocked automatically as you progress through the story and share the same slot in the gallery. To unlock [Jilted] refuse the marriage proposal. To unlock [Hitched] accept the marriage proposal.

CG 12: [Damned]

To unlock this CG, you must reach the "You are the Damned" Ending. More info below in the endings guide.

CG 13: [Exsanguinated]

To unlock this CG, you must reach the "Sacrifice" Ending. More info below in the endings guide.

CG 14: [Run For Your Life]

To unlock this CG, you must be on the path for the "Sacrifice" Ending and succeed with the final quick time pop up that says "RUN!". It will probably help if you save the game regularly as soon as you're back playing as MC again.

- Endings - 

Ending 01: [You are the Damned] 

In order to reach this ending, you only have to do one thing. Make sure that when you enter a name for MC at the beginning of the game, that you put the word Dawn. It doesn't have to be 'Dawn' specifically. Entering the equivalent translation of the word/name 'Dawn' in most languages will result in you getting this ending. I tried my best to include as many languages as possible, but I am no expert, so I was relying on a mixture of Google translate and websites that claimed to list the translations for the word 'Dawn' in all languages! 

For this to work, you have to enter it beginning with a capital letter with the rest lowercase like this: 'Dawn' OR all lowercase like this: 'dawn' If you enter the name in all caps, or in a weird format like: 'daWn' it won't work.

If you enter the word for Dawn in your language and you don't reach this ending, feel free to contact me and let me know what the word is, I will then try my best to get it added to the game :3 I can only apologise if it is missing or if I've managed to misspell it >.< For a full list of all the names that currently trigger this ending, please scroll down to the very bottom of this post.

Ending 02: [Sacrifice] 

Make sure not to name your MC any of the cursed names when entering a name at the start of the game, and don't click on the final quick time pop up that says "RUN!". You can click on "Sneak away" and "Hide" if you want to, as these are traps, and will still result in the [Sacrifice] ending.

Ending 03: [Run For Your Life] 

This is a sorta silly/troll ending x3 Make sure you haven't named your MC any of the cursed names at the beginning of the game. After finishing playing as Morgen, when you are back to playing as MC again at the antiques place, don't click on the quick time pop ups for "Sneak away" or "Hide" (these are traps). Make a save when Dämmerung says the following line:
"You can't die, not truly. You'd be forced to wither away in silence only to be stuck inside an ugly shell upon your demise. You need me just as much as I need you. Like it or not, we're bound to each other, so why bother protesting?"

Once you advance the text, a pop up saying "RUN!" will appear. You only have 0.75 of a second to click on it. If you are successful, you will get this ending and unlock its corresponding CG.

- List of Cursed Names -

"Dawn" "dawn"

"Aurora" "aurora" "Aurōra" "aurōra"

"Hausos" "hausos"

"Eos" "eos"

"Morgenröte" "morgenröte" "Morgen" "morgen" "Morgendämmerung" "morgendämmerung"

"Aube" "aube"

"Amanecer" "amanecer"

"Alba" "alba"

"Świt"

"Jutrzenka" "jutrzenka"

"Brzask" "brzask"

"Pассвет" "pассвет"

"заря"

"начало"

"黎明"

"Límíng" "límíng"

"破晓"

"晓"

"夜明け"

"よあけ"

"Yoake" "yoake"

"明け方"

"黎明"

"새벽"

"Saebyeog" "saebyeog"

"시초"

"فَجْر"

"Amanhecer" "amanhecer"

"Alvorecer" "alvorecer"

"Zora" "zora"

"úsvit"

"Daggry "

"Dageraad" "dageraad"

"Agim" "agim"

"світанак" "Cвітанак"

"Egunsentian" "egunsentian"

"Pазсъмване" "разсъмване"

"Koit" "koit"

"Valjeta" "valjeta"

"Dage" "dage"

"αυγή"

"Hajnal" "hajnal"

"Dögun" "dögun"

"Breacadh an lae" "breacadh an lae"

"Rītausma" "rītausma"

"Aušra" "aušra"

"Sonnenopgang" "sonnenopgang"

"зори"

"Bidunett" "bidunett"

"Soloppgang" "soloppgang"

"Zori de zi" "zori de zi"

"Madainn" "madainn"

"зора"

"Svitania" "svitania"

"Gryning" "gryning"

"таң" 

"Cвітанок" "світанок"

"Svitanok" "svitanok"

"Wawr" "wawr"

"פאַרטאָג"

"լուսաբաց"

"Sübh" "sübh"

"ভোর"

"પરોઢ"

"भोर"

"таңсәрі"

"ਸਵੇਰ"

"รุ่งอรุณ"

"ڈان کی"

"Tong" "tong "

"Bình minh " "bình minh"

"שַׁחַר"

"Bandev" "bandev"

"Aanbreek" "aanbreek"

"Madaling araw" "madaling araw"

"Wanaʻao" "wanaʻao"

"Fajar" "fajar"

"Subuh" "subuh"

"Ata" "ata"

"Tafa o ata" "tafa o ata"