The original concept was named Nostromo, a reference to the spacecraft from the film, with the attraction's alien planned to be the titular Xenomorph creature, and X-S Tech was going to be the Weyland-Yutani Corporation.

As a result, the name Nostromo was taken out entirely and an original alien was created for the ride and the fictional company was changed to X-S Tech.

This version's storyline had X-S Tech's open house being a front for exposing human guinea pigs to an alien monster they had captured.

The X-S scientists respond by trying to destroy the test chamber and leave no evidence, but the alien holds off their weaponry, raises the restraints allowing the guests to escape.

[4] Extraterrorestrial Alien Encounter was proposed for Disneyland for the "Tomorrowland 2055" project as part of the "Disney Decade," started by then-Disney CEO Michael Eisner.

[citation needed] Upon its opening, some Disney fans praised Extraterrorestrial Alien Encounter for its darker tone in contrast to other attractions at Magic Kingdom.

[3] Extraterrorestrial Alien Encounter closed on October 12, 2003, and was replaced by Stitch's Great Escape!, which opened on November 16, 2004 and operated until January 6, 2018, using much of the same technology and set pieces from its predecessor.

Before the start of the pre-show, the television monitors described other events taking place at the Tomorrowland Interplanetary Convention Center, including "The Tomorrowland Chamber of Commerce presents X-S Tech", "Mission to Mars: History or Hoax" (a tribute to the attraction that previously occupied the Alien Encounter building), "Championship Pet Show", and "The Walt Disney Company's Pan Galactic Stock Holders Meeting", featuring a holographic transmission from "Lunar Disneyland—The Happiest Place Off Earth".

Clench and two X-S Tech employees, Spinlok (Kevin Pollak) and Dr. Femus (Kathy Najimy), communicated "live" from across the galaxy via video screens.

A maintenance worker attempted to restore the power, but was mauled as the alien's shrieks resounded throughout the room and a spray of fluid flew out into the audience hitting the guests' faces.

Unlike its successor Stitch's Great Escape!, much of Alien Encounter took place in total darkness while the attraction engaged guests' nonvisual senses.

Warm moistened air was used both gently, to simulate the alien breathing down the audience members' necks, and forcefully, to induce a more intense reaction from them.

[citation needed] During lighted segments, the show used lasers, rear-projected screens repurposed from the previous attraction, Mission to Mars, and Audio-Animatronics for the alien, SIR, and Skippy.