Its possible to have BGM (music in game), its optional.
Here is instruction https://wikiwiki.jp/id-a/Memo#n15fd8bb
remember to correctly change that string
private var bgmurl:String = "bgmファイルをおいてるフォルダ";
to
private var bgmurl:String = "bgm\\";
then create bgm folder in your inishie dungeon folder
You can skip part below with wayback machine by downolading this file with every repuired BGM
https://www.dropbox.com/scl/fi/e9srxcc4m15g7pl70c5r8/bgm.rar?rlkey=ghajmbkacaep6...
go to Wayback Machine and downoland every BGM link from 2020 clicking on it with right click and "save link as" , some links have 2 captures inside so first click on it and choose 1 link.