One-sentence story building

Then a friendly stranger appeared in front of him after a gust of wind.
???: hello there.

NSS: if i see something that might get the thread closed i will use the kraken on it.

John: nah man, don’t worry, that crap ain’t gonna happen this time. i got rid of the others.
suddenly a blonde woman appeared behind him
Rose: John, you traitor!
John, choking: rose, i had to do what i had to do!
Rose: I don’t care, John, you killed everybody! You even killed Kirby! Do you know what that means?
John: uh oh…

and then a giant rockworm from the game floatin’ noclipped into levels 2 and 3 of the backrooms and started tearing up the entire thing while destroying parts of 8 floors at all times because there were no big enough rocks for them to fit in

And they get attacked by the army of Kirbies.
Meanwhile…
John: oh. hi, kirby. no hard feelings?
Rose: I thought I could love you, but you betrayed me. You betrayed US. all of us! Sick 'em, Kirby.
Kirby: Aye! proceeds to slice John in half with an Ultra Sword
John: I’M SORRRRRYYYYYYY! AUGHHHHHHHH!

but due to the rockworm being 8 stories tall and wide while having its own ecosystem and an iron shell because of no meteors the kirbies do nothing and actually get eaten instead by the rockworm’s resident ectosymbiotic animals

NSS: well, crap.
Meanwhile:
Rose: Any last words?
John: i’m sorry…
Rose: Sorry doesn’t cut it, love.
Rose zaps the two halves of John, causing him to die a Just death
Kirby: Hmmph.

and then they all get eaten by a rockworm that then eats up to the surface through a moss tower that is hundreds of meters wide

Rose: Well, this is karma. I just killed my ex, and now I get killed?
Rose: Just great. All our friends are dead, Kirby.
Kirby: Ugggh?
Rose: What is it?
Kirby: points to the fake Kirbies nearby
Rose: Really, These guys AGAIN?

after getting to the area where it has enough space to properly grow and reproduce the rockworm excretes several thousand rockworm eggs which have photosynthetic copepods that were too small to properly have cells and thus turned into one cell in them to get oxygen and energy in the air

(Kirbies): all Inhale on Rose simultaneously like a horde of zombies
Rose: AAAAAAAAGH! gets torn to shreds
Kirby: Hmmph! turns into Hypernova Kirby and sucks up bucketloads of fake Kirbies

the majority of the rockworm eggs fall to the ground and go splat thus introducing new species to the ecosystem of the backrooms roof and making it possible for blood to exist but some of them fell into water and had water on them allowing them to survive and grow into more rockworms

Kirby continues to suck up the Kirbies and blasts them into the walls of the Rockworm, damaging it
Rose respawns because her death was neither Heroic nor Just
Rose: What the hell? They tore me apart, literally!
Kirby: shrugs
Kirby shoots more Kirbies at the wall of the Rockworm, and it spits them out

the rockworm is not damaged because it is not even in the same area as them as it is above the surface so far up that nothing other than a rocket could reach it and its offspring start hatching and devouring the wildlife because worm

Rose: We’ve gotta stop these worms! But how?
Kirby: Hup! uses Mecha on them and they start attacking
(Kirby): Hmph! Sucks up Rose while nobody is looking and gains the Needle ability

the worms eat them all starting with their brains for the humans and the membrane for kirby and grow large enough to be hollowed out and used as a house because they can be in the soil or several thousand kilometers up or anywhere in between and thus can sneak up on them from any angle

Rose gets posseessed by the worms, while the two Kirbies die of getting their insides eaten, but also because any attempts to possess or assimilate them just kills them
2 lives left for both
they both respawn elsewhere in Level-1
Kirby: Uh oh…
(Kirby): Huh?
Kirby: gestures to a human having a worm eating their brain

after the worms possess rose they start hunting moss creatures and gathering fibrous plants to make bone tools so they can advance technologically.

NSS: done, but i had to get rid of most of the story in the process.
Back to the story.
(Kirby): gasps nods in agreement that they have to get rid of the worms somehow
Kirby: shrugs as he doesn’t know how that is possible
(Kirby): gestures to one Kirby multiplying into many more Kirbies
Kirby: Hup!
they then start multiplying until they recreate the Kirby Army, meanwhile…
Rose?: Now to clobber those there Kirbies…

after making gloves from moss creature hide rose starts looking for moss with big spikes to make a kirby killing spear to defeat the kirby army.