User blog comment:Brother Demnos/Horus Heresy Game on RPGXP/@comment-3459279-20120807205729

to not mess with canon I would suggest that you don't allow players to play as Primarchs, because of the strictness of the lore. You could set up the story so that the players play as a 'champion' of a primarch, or of Horus and the Emperor (thus changing the final battle to take place during the Horus vs Sanguinius or the Emperor but between champions). This also allows you to simply toss in an extra character during the battles that took place. If you are choosing the legion for the player then you have options of certain tactic choices, but if the player chooses that adds more complications to the game. I think that you should focus on major battles, with maybe adding a few between sides if you need more, otherwise I dunno what you might need for more ideas..just follow the novels