Star Fox orchestrated soundtrack (unreleased video game arranged soundtrack album; 1990s)
Star Fox is a Nintendo video game released on the SNES from 1993, the first game in its eponymous Star Fox series. Its soundtrack was composed by Hajime Hirasawa, who was an employee of Nintendo at the time, but who left the company immediately after the project, due to disagreements over the rights to his music.
According to a "devs play" interview with Dylan Cuthbert (a programmer on the game), apparently Hajime Hirasawa had fully completed an entire album of orchestrated arrangements of the music he wrote for Star Fox, which his prior career in the music industry had to lead him to assume he would be free to publish. However, Nintendo informed him that the music he had written for Star Fox belonged to Nintendo and not to him. The two parties were not able to reach an agreement over the rights to the album, leading him to leave the company and abandon his plans to release the album.
Dylan Cuthbert said in the interview that he had a copy of the album on tape, and may in fact still have it, but implied that he doesn't know where the tape is right now. (He suggested that he may be willing to sell the tape upon finding it, but that might have been in jest.)