Cytus

Cytus features a story plot that is carried through its 10 main chapters as well as a prologue. The story revolves around the protagonist, Vanessa, who lives in a 22nd-century world where robots with human memories are the only remaining sentient beings while living humans are killed by a mutant virus. Due to limited memory space, human emotions are stored in the form of music in "Cytus", and by playing the songs, the robots are able to revive their human emotions. (wikipedia.org)