Once the UFO has been shot down the player can send in a transport of soldiers to carry out a tactical mission to neutralize the aliens and capture their equipment.

Aliens can attack the player's base with UFOs, in which case it is a fight between your SAM sites and the UFO; if the SAM sites are destroyed, a tactical mission within your base will take place (or aliens will take it over in which case the player needs to send a transport ship).

In the year 2023 the spaceship Magelhaes finally reaches the planet Esperanza and the people on board quickly begin development of a colony.

Several governments take control over the different continents and all was good until one day in the year 2025 a squad of pilots encounter a unknown alien force and get shot down.

[6] Eurogamer said it is a flawed clone and recommended it only to X-COM fans who couldn't wait to see what 2K Games did with the license.

[8] The August 2008 edition of Pelit featured a retrospective of UFO: Extraterrestrials that focused on the effects mods have had on the game.

He focused on "Bman's Ease of Use Mod 4.07 (fixed by Coasty)" as the prevailing merger of minor modifications, and pronounced it "the true successor of [UFO: Enemy Unknown]" that "genuinely achieves some of its predecessor's magic."

In September 2009, Chaos Concept unveiled a new website announcing a prequel, UFO2Extraterrestrials: Shadows over Earth, which has been in development since early 2009.