With the release of (the "Age of Darkness" edition), the demand for updated digital rules has spiked. Players typically look for: Core Rulebooks: The foundational mechanics for 2.0.

Specifically the Liber Astartes and Liber Hereticus , which contain the army lists for the Space Marine Legions.

4plebs is a popular for various imageboards, most notably the /tg/ (Traditional Games) board of 4chan. Because imageboard threads are ephemeral and disappear after a certain amount of time, 4plebs allows hobbyists to search through years of discussions, tactica, and shared resources.

Look for threads titled "HHG" or "Horus Heresy General." These usually contain a "pastebin" or "op" link in the first post that directs users to a collective library.

The /tg/ community can be abrasive. If you are looking through active threads rather than archives, it’s often best to read the "OP" (Original Post) thoroughly before asking for links, as they are usually already provided. Why Digital Versions Matter