My Horus Heresy opponent and I were talking about starting up a 40K campaign down the road, and I got inspired. What a great way to fully break in my Chaos Guard, and it would help motivate me further to get them table-ready. I'd play the Chaos Guard in the campaign, and he would bring his Blood Angels, Black Templars, or maybe both.
This is the prototype; as I tinker and with feedback from him the flowchart and the missions may change, but I wanted to go ahead and share. I really like the flowchart - provides for both the possibility of a quick end, but also the chance to loop back around, allowing a player with early setbacks a chance to struggle back to total victory as long as the campaign hasn't reached the last row. "CV" stands for Chaos Victory, "IV" for Imperial Victory. The outcome of the last mission (the 5A->5F choices) determines the victor/level of victory, running from Total Chaos Victory if Chaos wins 5A on the left all the way to Total Imperial Victory if the Imperials win 5B all the way on the right.
I'll put up the mission details next.