Earth and Sky is an interactive fiction

Interactive fiction

Interactive fiction, often abbreviated IF, describes software simulating environments in which players use text commands to control characters and influence the environment. Works in this form can be understood as literary narratives and as video games. In common usage, the term refers to text...

 trilogy written by Paul O'Brian about the adventures of a brother and sister who gain superpowers

Superpower (ability)

Superpower is a popular culture term for a fictional superhuman ability. When a character possesses multiple such abilities, the terms super powers or simply powers are used...

 while searching for their lost parents. The first part, Earth and Sky was entered in the 2001 annual Interactive Fiction Competition

Interactive Fiction Competition

The Interactive Fiction Competition is one of the best known of several annual competitions for works of interactive fiction. It has been held since 1995. It is intended for fairly short games, as judges are only allowed to spend two hours playing a game before deciding how many points to award it...

 where it finished eighth. The second part (Another Earth, Another Sky) was considerably more successful, winning the competition in 2002 as well as picking up the 2002 XYZZY Award for Best Use of Medium. The third part, Luminous Horizon, also managed to win the Interactive Fiction Competition when it was released in 2004.