During this time, Space Marines were not the monolithic, standardized force they are often perceived as today. While the "Codex Astartes" was a fictional document written by Roboute Guilliman, the game rules treated the various Chapters quite differently. Before the release of this specific codex, Space Marine players had to rely on "Codex: Angels of Death" (which covered Blood Angels and Dark Angels) or the basic black-and-white army list booklets included in the starter box.