Gremlin Invasion was set within a fictional movie theatre. The pre-show was a showing of classic movies, which gets disturbed by Gremlins on the loose. During the actual ride Gizmo and ALF guide guests through a variety of movie sets, in which Gremlins were playing tricks.
Gremlin Invasion was based on Warner Bros. Classics and The Great Gremlins Invasion at Warner Bros. Movie World (Gold Coast, Australia), which opened a few years earlier. However, instead of the character 'Beetlejuice' (from the Tim Burton movie) as a host, it featured 'Alf' (from the TV-show of the same name).
Gremlin's Invasion closed at the end of the 2004 season when the park transitioned from Warner Bros. Movie World to Movie Park Germany. It continued to be used only during the Halloween season, with the sets hidden from view but was otherwise standing but not operating until it was replaced by Van Helsing's Factory in 2011. One of the animatronic Alf characters can now be seen in the operator cabin of a crane in Van Helsing's Factory as a nod to the old dark ride.