Source plot synopsis — includes the ending
As they gather parts to build the rocket, Astrid is contacted by the Ancient Signal that controls the machinery there, warning her about an imminent danger, when the rocket is completed, Core reveals himself as part of the Vectron Hivemind, who deceived the bots into build the rocket so they can escape the planet. Pursued by the Vectron machines, Trader stays behind, sacrificing himself to allow the others to escape the planet. Once in space, the bots depart to look for a new home to settle, unaware that the Vectron Hivemind has infiltrated their systems.
Sources and content license
Source and revision history ↗ · Adapted from Wikipedia contributors, SteamWorld Build. Section headings and formatting adjusted. · Content license