From the author's README on Thunderstore

Music from Library Of The Untold Esoteric Documentaries

Playlists & Tracklist

Sidirial

Sidirial - Bloodtide
Sidirial - Children Of The Deep
Sidirial - Primordial Ecstasy
Sidirial - Cocoon of Tormented Languages
Sidirial - Madness Divine
Sidirial - Gift of Poison
Sidirial - .
Sidirial - Center of Faceless Chaos
Sidirial - Great Dreame

Installation

Install via Thunderstore Mod Manager, or drop into your ReSkate launcher.

Packaged with ReSkate Music Packer

Install Sidirial

You need ReSkate and your own copy of skate. on Steam.

Open ReSkateLauncher.exe and go to MODS.
Search for Sidirial and click install. The launcher also installs anything it depends on.
Press PLAY. In game, the MODS tab of the ReSkate menu (Insert) turns it on and off.

Or install it by hand: download the .zip and drop it on the launcher window, or unzip it into its own folder in Mods\ beside Skate.exe.

Maps show up in the ReSkate menu's level list. To join a server running a custom map, you need the same map installed. If the game won't load after installing, see known issues.

skatemods doesn't host or review this mod. The download comes straight from Thunderstore. Only install mods you trust, because scripts can run code.