Princess of Worlds End

On the ark “Maritime Mobile City GFM Oceanos,” inhabited only by busty swimsuit beauties, the visitor Neptes must battle the threatening “Deep Ones” and uncover the mystery of the “Great Mother Goddess of the Abyss.”

Year 2055. Tokyo.
Wars, resource depletion, and population decline.
In this place filled with despair, the bright girls perform live streams. Being evaluated and ranked in this world, their eyes become increasingly clouded.
In this colorless, dark world, a girl awakens.

“HELLO WORLD! I am Ai from Vstar!”

The girl continues to sing until the world ends, shining in the despair.
 

A long time ago, in a galaxy far, far away there exists a Galactic Empire ruled by Emperor Paipatine the 6969th. The Empire has been warring with rebels for many years, and both sides desperately desire something to boost their spirits from the fighting... And that's where our hero steps in. Squid Inkwell, a tentacalien, is itching for his opportunity to conquer another planet to expand his species's joy-bringing enterprise, and that time has finally come.
 
Capture the people of Earth using your powers as a tentacalien, putting them to work at your operation in order to pay your dues to the Galactic Empire and take over the planet. Also, don't forget the most important thing... placing the top brass of the world under your feeler!

The world was once shrouded in an eternal twilight.
At the foundations of the continent, the abyssal rift collapsed. The Dark Lord fed upon despair, commanding a legion of the dead to crush civilization into ash and dust. The gods fell into a deep slumber; kingdoms crumbled to ruin.
Only one remained: a Witch, feared and exiled by the people, who had inherited the ancient, forbidden powers of Darkness and the Stars. She seeks no salvation, nor does she ask for pity.
To sever the cycle of dark reincarnation, she steps alone into the cursed wastelands. With a scythe as her blade, she carves a path through corpses and lamentations, defying the odds to reach the Dark Lord’s obsidian throne—sworn to a singular, final act of vengeance.
This is a war to strike down the dark with despair, and to incinerate the abyss with a solitary, indomitable courage.

The girl opens her eyes in a desolate world, and hears "your" voice from in front of the screen.
You can direct her actions, help her solve mysteries, evade dangers, and find a way to leave this place. Of course, you could also choose not to do so, or even worse, deliberately guide her to death... Just kidding, you surely wouldn't do that, right?