Looking at unmade Science Fiction, Fantasy and Horror films and television…
Plans were made to continue Stargate: Atlantis as a movie (or a series of movies) after the season 5 final.
[The following may contain brief spoilers for Stargate: Atlantis.]
Stargate was a successful 1994 science fiction adventure film which lead to a TV series continuation Stargate: SG1 (1997 – 2007). The series had its own spin-off Stargate: Atlantis spinning out of plotlines in season 7 and 8 of the parent show.
SG: Atlantis went for 5 seasons, but was not renewed for a sixth season and end IN 2009 with the city-ship Atlantis cloaked on Earth off the coast of San Franisco
Showrunners hoped to continue SG: Atlantis & SG-1 with three or four telemovies (or straight to DVD movies) a year (depending on the movies’ success) following the success of the SG-1 movies Stargate: The Ark of Truth and Stargate: Continuum in 2008.
Stargate: Extinction, the first planned SG: Atlantis film would begin with Atlantis no hidden on the moon, when the sudden sounding of a self-destruct alarm would force the crew of the Atlantis to make a series of jumps back to the Pegasus Galaxy.
During this period MGM who made the shows declared bankrupcya dn in 2011 it was announced that all plans for Stargate movies had been dropped, thus ending all hope for SG: Extinction. When series that replaced SG: Atlantis, Stargate Universe ended after 2 seasons a couple of months later, it signaled the end of the Stargate TV franchise. Creators of the original film Roland Emmerich and Dean Devlin have since declared their intention of completely the trilogy they originally intended by remaking the original film.
A long-term release schedule in 2014 for Boom! Studios included a four issue comic book adaptation of SG: Extinction but was quickly removed leading to speculation that the idea was in discussion but never finalised and no Stargate products have been officially announced.