Superweapon
In recent years the Collective has developed a MacGuffin of untold power, able to motivate entire species to really, really...do things.
If the Collective is able to field the weapon, they would be able to instantly take control of all the sentient minds on an entire planet. That was motivation enough for Draco to devise a scheme to steal it away from them, and motivation enough for them to stop at nothing to reclaim it from him.
When Draco brought the weapon to Earth for safekeeping, unaware that Earth is populated, humanity is caught up in all this dang-blasted motivation, and has to defend itself from alien marauders.
This technology has not been researched yet, and it probably never should be. If the players have access to it, they probably don't even want to see what kind of bad guys come out of the woodwork; like finding the BFG-9000...you just know something awful is lurking nearby.
