Key defines "Planetarian" as a "kinetic novel", since its gameplay offers no choices or alternate endings. Instead, the player proceeds through the story solely by reading. The story is written by Yūichi Suzumoto and "Planetarian" is one of two Key games not to have Itaru Hinoue as an artist, using Eeji Komatsu instead. The game's soundtrack was composed and arranged by Key's signature composers Magome Togoshi and Shinji Orito.