Alright guys, I'm almost ready to release the chapters. I already have five finished and ready to upload. They are partly a summary of the MC's life (the idea is that he was a covert-operations operative a Terran Ghost. He has high psionic abilities, but nothing insanely overpowered. His main motivation was avenging the old Emperor after the betrayal of his son. After a failed rebellion led by another rebel leader, he ended up waging a guerrilla war against the Empire, and that's when he ends up in the terrifying universe of Warhammer 40k).
I have two questions here:
First, start directly in Warhammer 40k—although I don't know that much about the setting—my friend promised to provide me with lore information to avoid making too many mistakes. Still, it's likely I'll mess up plenty of things.
The second option is waiting and going for the Byzantine Empire storyline once I have a better grasp of the historical background, while we research books and get proper material to study everything carefully.
If you choose the Byzantine option, I'm planning to make something shorter, around 120–150 chapters. I want to show the brutal living conditions of the era, as well as how the MC slowly becomes corrupted by the Byzantine system.
If you still prefer to go with Warhammer 40k, my idea is that they arrive around M38, during the Tau Second Sphere Expansion, making the Tau their main enemy. I like that setup because in a way they're balanced: the Tau have the numbers and the Terrans have superior technology, and I want to show how both sides tear each other apart—unless someone recommends something better. The Koprulu Sector from SC2 is located in the Damocles Gulf, which is precisely where the Terrans would end up arriving.