The game opens with a cutscene explaining the Alien Alliance’s reasons for invading Earth. It may be a resource-rich planet but the Alliance aren’t invading the planet for its resources. It’s invading to save Earth from those vicious murderous cancerous organisms, those so-called Humans.
A montage showing these Humans’ various transgressions is shown. Quick cut from a scene showing caged chickens to the shocked countenances of the Alliance representatives from Avian.
This isn’t Invasion: Earth.
This is Rescue: Earth.
That this alienitarian rescue mission, if successful, will see the Alien Alliance gain control of a resource-rich planet just begging to be exploited is completely irrelevant.
Ahem.
The game begins with the player in control of a small platoon of Sectoids and a tiny Scout-class ship. Your initial goals include exploration, obtaining specimens (alive or otherwise) and establishing advance bases. The player will soon have to contend with X-Com, Earth’s defense force, with initial battles being small hit-and-run affairs as both sides size each other up.
As the campaign progresses along the winning branch, other alien factions from the Alien Alliance, eager for a share of the spoils, join the Sectoids in the invasion. The Chrysallid follow after the Sectoids, then the Snakemen and the Mutons shortly after that, with more exotic alien factions joining in later.
The additional alienpower, skills and resources will aid immensely but keeping the various alien factions happy will not be easy at all. Players will need to juggle missions in order to satisfy various factions’ needs. The Sectoids want new technology and new knowledge (this involves research, acquiring specimens, anal probes, etc.), the Snakemen crave territorial expansion (claiming enemy territory, creating and expanding bases), the Mutons want glorious battles (large-scale battles and base invasions), the Chrysallids have developed a taste for human flesh and thus require the capture of live humans … Fail to keep a faction happy for an extended period of time, and it will pull out of the war effort, making the campaign tougher.
To further complicate matters, there are dissenting voices among the Alien Alliance who are against the invasion. Their view will gain traction the longer the campaign drags on and the more losses the Alliance sustains. Victory alone is insufficient; it must be victory at minimum cost.
The longer the campaign takes, the more technogically adept X-Com becomes. Every mission lost sees the enemy improve dramatically as they reverse-engineer alien technology, making subsequent battles significantly tougher.
Fail your missions enough times and the invasion is called off, resulting in the Alien Alliance negotiating a peace settlement with Earth on humanity’s terms. Those terms will never be known to you, player, as the punishment for failure is a black screen, a shrill alien scream and a ZZZAP!