Cell to Singularity uses recordings of classical music, most of which are in the public domain. Here is a list of music used in the game.
New World Symphony : Largo - Antonín Dvořák (Opening the game)
Waltz of the Flowers - Pyotr Tchaikovsky (Primordial Soup)
Prélude à l'après-midi d'un faune - Claude Debussy (underwater segment)
Bolero - Maurice Ravel (On Land)
Concerto For Orchestra - Béla Bartók (game moments)
Jupiter Dance : Planets - Gustav Holst (game moments)
Mars : Planets - Gustav Holst (game moments)
The Moldau - Bedrich Smetana (Civilization)
At the Terminus of the Blue : Music of the Hoh River Valley - ©2010 Prent Rodgers (Reality Engine)
Vox Humana - ©1999 Marchthirtyseventh (Unlocking Humans)