This specific update generally includes various balance tweaks and bug fixes implemented by the developers, Bulwark Studios, after the initial launch.
The string refers to a specific scene release of the Heretek expansion for the tactical game Warhammer 40,000: Mechanicus .
The Warhammer 40k Wiki defines a "Heretek" as a Tech-priest who defies the Cult Mechanicus to pursue forbidden technologies. In the context of the game, this expansion introduces: