Post-nightcore
Beginning in 2016, post-nightcore (also known as nightcore revival) has
been extending nightcore into experimental and artform territory.
Some approaches include speeding songs up far beyond the typical nightcore
30%, rendering samples unrecognizable, sampling songs that have no business
being nightcored, and burying nightcore behind noise and glitch elements.

Selected artists:
Arashi-bu
Favorite 水
Plastic Neesound
歳納さん
NEOCAFE
more ? sugar

Labels associated with post-nightcore:
ČERNOBOG
Pedicure Records
Ecco Gang Records

Deep internet
A form of found sound / plunderphonics using samples, both musical and not,
from youtube videos with under 20 views (often found using Petittube.) Though
it was created by a /mu/ thread, it quickly became a larger phenomenon on bandcamp,
and though it's activity level has decreased since it's creation, releases still
tricke in. Also see this for influences.

Notable artists:
torrent my pets
sorryman
Quiz MVE
white uploader

Kusoikore
A subgenre of breakcore/lolicore started by CDR defined by it's usage of
high-speed distorted amen breaks, noise / glitch elements, and not taking
itself particularly seriously.

Notable artists:
CDR
XoArK
Himeko Katagiri

Notable labels:
RDC Records
Tsundere Violence
HM Records
The Worst

Comfy synth
A relatively recent offshoot of dungeon synth that relies less on dark melodies
and bleak imagery and more on warm sounds and aesthetics. Hobbits, animals, and
cottages are common themes.

Notable artists:
3 little kittens
Olde Fox Den
Grandma's Cottage
Tiny Mouse

Digigrind / midigrind
In the 2000s and early 2010s, digigrind (also known as midigrind) was created,
primarily fueled by a community on MySpace. It combined chiptune and midi
instruments, screamo/grindcore vocals, gabber kicks, and an array of other
personalized influences. It can be traced back to 1999 with acts such as
Stagedive Suicide / Ranger Raccoon, and over the 2000s attracted many
new bands, including Bubblegum Octopus (spazzpop creator) and Hara-Kari Kitty.

While it declined over time due to the collapse of MySpace, some dedicated
artists continue (primarily on Bandcamp) and it's influence lives on in
scenecore and associated communities.

Notable artists:
Stagedive Suicide / Ranger Raccoon / Adam Cooley
Bubblegum Octopus
Hara Kari Kitty
Hello Kitty Suicide Club

Notable labels:
Kitty on Fire Records
Brokecore

Ambient noise wall
ANW is a variety of HNW that places less emphasis on crushing and distorted sounds
and more on quieter and gentler textures while still mantaining the wall aspect.
Tracks are less of blasts and more of crackles, and rarely employ the edgy visuals
that are often seen in HNW.

Notable labels:
Avocado Tapes
Terrarium

Lobit
I'm unsure if this is best described as a genre or recording style, but it seems
to belong here either way. Lowbit is a type of music characterized by it's low bit rate
(typically somewhere between 96-8kbps,) using heavy mp3 compression as a technique
instead of an issue. Releases range from being simply lofi to being comprised almost
entirely of audio artifacts.

Instead of providing a list, check this out instead. Emphasis on 8 Ravens.

Crushed Trap
Spawned by the infamous-in-certain-circles "Rare RCB hexD.mp3", crushed trap
(also known as hexd, also known as surge) is characterized by foggy synths,
trap influence, and lofi / bitcrushed recording. Emo culture and 2000s imagery
show up promentently on releases. Perhaps put best by a youtube comment:
"accelerationist soundcloud rap"

Notable artists:
Reptilian Club Boyz
Hi-C
dismiss yourself
YABUJIN

Planned additions to this list: a guide to next year's snow collective