Characters who are grey and vanish have been linked to W.D. Gaster, who is a secret character in the game's files. We still don't know much about Gaster, except that he seems to be a skeleton (and possibly related to Papyrus & Sans) and was the royal scientist before AlpThe soundtrack comes with two discs. This means you’ve got access to the complete soundtrack (which is over 100 songs). A digital download is not included, but most Undertale megafans probably already have the soundtrack digitall...