Just had an epiphany on how to make use of the Codex Astartes (or rather knowledge of it) in game:
Normally I don't allow too much communication between players during combat (that is in Cyberpunk or Fantasy games). However, the Codex Astartes represents the sum of Astartes battle lore of millenia, codified and systematically structured.
So as a result I think I will allow players belonging to codex-adherent chapters to freely communicate with each other in combat. A complex tactical advice might in-game break down to "Brother Titus, Cania protocol, verse 14, section B". Every member of a chapter that adheres to the codex will understand. If the communoication is very complex, interrupt the player and have the receiver make a codex skill roll to continue the discussion.
Non-codex chapters will either have developed their own battle lore and communicate with each other in a similar way but cannot exchange in complex exchange with codex chapters - or they rely much on instinct anyway (I'm looking at you, Space Wolves). If they have the Codex skill though, they may understand with a successful roll. Very complex debates will demand more difficult roles.
Not bad for an ad hoc idea. Now I only need a good ruling on how to integrate/combine codex astartes lore with tactics and I'm good to go.
Alex
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