"Closedverse OST" refers to a trend on Closedverse where users would post music tracks, usually of video game music, and refer to them as if they were a theme for a particular user or event on Closedverse. Users tended to post music tracks that they associated themselves with as their "theme". "Closedverse OST" would refer to two separate projects by different Miiverse clone users: one by the user fanficc (otherwise known as nice >:]), and another by the user Big Boy (otherwise known as K-Man).
"Album art" for Closedverse OST.
Sometime in late 2017 or early 2018, the user fanficc used a bot to gather posts that started with "Closedverse OST - ". The bot extracted the "title", the username of the poster, and the embedded YouTube link. He used this bot to create a "Closedverse OST", using existing tracks renamed to fit the Closedverse theme.
On January 7, 2018, fanficc posted the completed Closedverse OST project, linking to a 1.8 gigabyte .zip file containing audio tracks renamed to fit the Closedverse OST theming, with 178 tracks in total, though 3 were excluded as the tracks were either not embedded or unavailable in the United States, where fanficc lived. According to his post, it took fanficc 10 hours to find the songs, download them, rename the files, and upload them. The folder contains two text files, one containing the track names alongside the users that posted them. The tracks are listed in the order of the users' posts. The contents of both text files can be found here. Additionally, the full list of tracks was posted to Pastebin on January 6.
The Closedverse OST file can be downloaded here.
Throughout 2018, the user Big Boy would compose original tracks to create a "Closedverse OST" based on user requests. He would compose various tracks that imagined Closedverse as a video game with character select music, boss battle music, and settings music, among other things. Following Indigo's release, he would also compose themes for individual users.
On March 13, 2020, Big Boy uploaded the .mp3 files of the music he could find to a Google Drive folder, and made it public. He was prompted to do so after the Closedverse Out of Context Twitter account made a post referencing the music tracks. In addition to the "generic" Closedverse OST themes and user-specific themes, Big Boy also uploaded compositions of requests he received on Closedverse, mostly for remixes of video game music.
The Google Drive folder can be found here.