what do you think he's listening to

undertale is the most beautiful thing to bless my ears
every soundtrack is amazing, to the last molecule.
with songs like Undertale, Hopes and Dreams, Death by Glamour, and Heartache, Undertale and the other games made by Toby fox have the most superior music compared to any other game.

I beg to differ on UnderTale's musical superiority. (And no i'm not saying it's bad)

Objection: geometry dash uses music produced on newgrounds, it does not produce music itself.
Because newgrounds is not a game, it does not count.

Fair enough. But i have one more argument up my sleeve. My... Ace Card.

Splatoon is a fighting game, so you don't even hear the music as often as the sound effects.
another thing, splatoons soundtrack doesnt have very much variety: Undertale does.

Splatoon's sound effects aren't as loud as you think they are. For me especially the music stands out, also the variety is through the roof! Varying from break core tracks like Splattack! (Octo) to 8bit bangers like No Quarters ALL THE WAY to upbeat melodies like spectrum obligato!

Undertales soundtrack has completely different types of songs, from Tense songs like Heartache, Happy music like SAVE The World, and others like Metal Crusher, Your Best Nightmare, Death By Glamour, Etc.

The same could be said about splatoon. It does different genres. From rock to pop

Heck! It even does some traditional too

Bro's listening to but the earth refused to die