Tumblr description from one of the artists:

Art for @vyl3tpwny song N I 4 N I.
Lineart by @quadrupedqueen
Color, Shading, & Background by me @dexterdaybreaker
Concept art below

Part of youtube description from Vylet Pony:

It's pronounced "an eye for an eye"

"NI4NI" was originally a 30 second, cut demo from my album "Monarch of Monsters". Its working title was "Jerk". Hakita ended up listening to this album and we had an exchange on Twitter which led to us planning this together. I hadn't played ULTRAKILL when he originally reached out, but it ended up becoming one of my all-time favourite games, facilitated by this project. It was a really fulfilling thing to work on, especially because with each demo I got a lot of feedback and critique from Hakita, helping to push this song in directions that I normally would be hesitant towards.

As of right now, I have over 70 hours into the game. I've P-ranked everything up to Fraud on Standard (excluding Minos and Sisyphus Prime, because whew). And my current Cybergrind high score on Standard is Wave 45. Jackhammer is the best weapon ever invented.

Thank you Hakita and Big Big Dave for the opportunity to do this track. Now go and play the game, and meet Aria (they/them) in the museum :)
AND, big shouts to Weavenest and Dex for coming through with this crazy artwork. You can see a full thread of their concept work on the V1 pony cover here