A setting or a history

[Ratboy1664]

40k is the setting for a game with unlimited potential for infinite possibilities. However 30k has already happened and is a historical fact, so do you the games player want GW and FW to push 30k as a (futuristic) re-enactment game i.e. set force lists, conditions etc or as more of a starting point for a possible alternative universe i.e the traitors can win and 40k doesn't exist? What do you prefer and why?

[Oir]

The Great Crusade lasted several centuries and spanned several thousand expedition fleets. The Horus Heresy lasted close to a decade iirc. I think there's more than enough room to work within the metanarrative of the setting without going into AU territory

[Raven Angel]

The Imperium is literally a nation that has forgotten its history. So from that perspective there is literally the same potential for games and narratives in 30K as in 40K.

[TennisBall]

30k after the scouring is pretty much 40k. Things don't really change for the next 10,000 years. The Emperor sits on his throne, the Legions are turned into chapters, the Imperial Army becomes the Imperial Guard and Navy and so forth.

You could do the Scouring of course as part of 30k. As much of the history is lost, you could have an entire campaign which results in the traitors capturing Cadia and turning it into a fortified outpost to defend the Eye of Terror from a possible invasion by the loyalists. The cadians back then had ties to chaos so it's not impossible. Cadia may have been a traitor bastion for a thousand years for all we know. 9000 years of Imperial rule erased that part from the history - there is a lot to play with.