A supplemental, community supported, mod for Cataclysm - Bright Nights, taking inspiration from XCOM 2, Half Life 2, the movie Skyline (not the sequels) and other similar 'alien invasion' media, as well as Harlan Ellison's short story "I Have No Mouth, and I Must Scream" to present a brutal game of survival against an alien expeditionary force.

NOTE: Really Dark Skies is much more difficult than vanilla Bright Nights, and is only recommended for players who have a lot experience under their belt, and players that move to love to add as many additional mods as possible.

• Many more people were twisted into hostile mutants by stray alien bioweapons. They are stronger than a vanilla zombie, but there come in smaller groups, usually, and have a few nasty variants.
• Alien soldiers, The Xenoids, occupy high-value targets and have deployed to the streets in order to pacify the cities for resources and neutralize threats. They each have uniquely debilitating psionic effects, a powerful melee weapon and an insidious dart gun.
• Invasive alien species prowl the wilderness, some hostile some are not.
• If you survive long enough, you may even see the Xenoid's emissaries to humanity.