The file is likely a segment of a multi-part compressed archive related to Ancient Cache of Technologies (ACOT) , a massive and highly popular expansion mod for the grand strategy game Stellaris .
: If you have the "Secrets Beyond The Gates" sub-mod enabled, you will face terrifying extra-galactic threats that require these high-tech tiers just to survive. 4. Compatibility & Performance
The ACOT mod transforms the late-game of Stellaris by introducing tiers of technology far beyond the "Dark Matter" tech of the vanilla game. 1. Technical Setup: Merging the Parts