planetarian ~ちいさなほしのゆめ~ ("Planetarian: Chiisana Hoshi no Yume", "Planetarian: The Dream of a Little Planet") is a science fiction visual novel developed by Key. Because it offers no choices or alternate endings, Visual Art's co.,ltd (the publisher) calls it a Kinetic Novel. It was adapted into a light novel and drama CDs.
It was later ported to the Playstation 2.
A Playstation Portable version has also been developed:
planetarian~ちいさなほしのゆめ~ 東北地方太平洋沖地震被災地チャリティー版
("Planetarian ~Chiisana Hoshi no Yume~ Special Edition for Tohoku Earthquake"). As the name implies, sales proceeds go directly to helping victims of the 2011 Japan earthquake and tsunami disaster.