"Universe (Let's Play Ball)" was composed by Carlos Battey, Wayne Hector, Breyan Isaac, Alexandru Cotoi, Marcel Botezan, Dem Jointz, Ryan S. Jhun and Kenzie, with the arrangement held by Issac, Cotoi, Botezan, Jointz and Kenzie.

[2] The song was composed in the key of F minor, with a tempo of 180 beats per minute.

[3] Described as an EDM hip-hop song with catchy hook, clattering percussion,[4] the lyrics, which were written by Kenzie and NCT U's member Mark,[1][2] talk about "espousement of fearlessness in terms of pursuing what one deems as his destiny", and also "made abundantly clear that a romantic interest plays an all-important role in his perception of achieving that goal".

[5] The music video, which was directed by Hong Jae-hwan and Beomjin, was released alongside the song by SM Entertainment on December 10.

[2] It features scenes of NCT U's members "challenging each other to a game of baseball, alongside shots of the group performing choreography".