The soundtrack to The End Is Nigh, composed by Ridiculon, consists entirely of rock remixes of classical pieces. The result is some pretty amazing tracks.
- The title theme is a remake of Gnossienne No. 1 by Satie. While it's nothing too overly fancy as it's almost the same as the original, with only a few gentle guitar riffs thrown into the mix, it's still a calming piano piece to keep you relaxed before the absolute Platform Hell you're about to witness.
- A very catchy 8-bit version of Mozart's Turkish Marchnote plays in Ash's game in the opening cutscene.
- "The End", a remix of Danse Macabre by Saint-Saëns and the theme for the first stage. Despite being a waltzy, Wild West-esque track, it still has a melancholy undertone to it befitting for the situation you are currently in
- The lively and fast-paced theme for the Arid Flats stage as well as its much slower in-game version are remixes of Dvořák's New World Symphony, which is already a pretty awesome classical piece to begin with. It has a rather angelic sound to it and is more optimistic in tone than the previous track, giving you the feeling that maybe there is hope during this Darkest Hour.
- Brahms' "Hungarian Dance" which plays in Retrograde. The theme contains a rhythmic electric guitar and is very fast-paced making it completely catchy.
- The game features two remixes of Grieg's "In The Hall of the Mountain King". One's a hardcore, metal-influenced track that plays in the final level, while the other is a peaceful, ambient piano/guitar track that plays in subterranean Mega Tumor rooms. Neither of them disappoint.
- "The Future", a remix of the "Dies irae" from Verdi's Requiem, is a powerful electric guitar and drum-heavy track that, as in the original, features Ominous Latin Chanting. Fittingly enough, it plays in some of the hardest levels in the game.
- "Acceptance", which remixes the second half of Liszt's Hungarian Rhapsody No. 2, is a climactic tune that fittingly plays in the last level as you Outrun the Fireball. Its use of chimes, sirens, and distorted guitar riffs in the beginning give it a surreal, ominous tone, and even has a guitar solo playing throughout the later, more frantic parts.
- While unfortunately only a bonus track, Wagner's "Ride of the Valkyries" deserves a mention. It's already well-known Awesome Music in the film world; imagine it in the world of video game music as a hardcore rock remix. In fact, Edmund McMillen was even considering using it as the theme for the S.S. Exodus stage, before settling on Tchaikovsy's Marche Slave instead.
- The credits feature the only original song in the game, but it definitely doesn't disappoint.