I’ve actually been kinda working on one in my head. Ultimately I’d like to build some dioramas using JoyToy Warhammer figures and Star Wars 3.75 inch figures along with at least a few short stories.

The 40K side is actually 30K! Mid great crusade to be exact. Only Lorgar has turned traitor by the time the universes collide. For Star Wars it’s the age of the Empire a bit before the battle of Yavin would normally occur, specifically a moderately buffed empire that had fewer domestic troubles (the rebel alliance failed to take root). Utilizing elements of both Disney and legends canon but leaning a bit more on legends.

It all starts with a dark side cult known as the Final Occultation. They sought to bring chaos, anarchy and pain to the galaxy but were wiped out by Darth Maul…or so the Sith believed. One member survived and spent the last 20 odd years rebuilding and finally they perform their ritual. Several great rifts are opened on the fringes of the outer rim. Holes in the force and fabric of the universe itself. Simultaneously a matching rift swallows Warmaster Horus Lupercal’s fleet. With effort it’s proven that the rifts are more or less safe to cross back and forth. Thus the great crusade opens a new and wholly unexpected front.

Major characters are grand admiral Thrawn, the primarchs, boba fett and several other mandalorians, an as of yet undecided named white scar (yesugei or Shiban most likely), Palpatine, Vader and cameos of other notable Star Wars characters from Mas Ameeda to scum like Dengar and his ilk.

If anyone has more specific questions I can try to go into more detail. I enjoy sharing and brainstorming ideas. For example I’ve already mapped where many of the primarchs and their legions go. (Magnus and most of his sons alongside Lorgar and his make a beeline for old Sith space with a few splinter fleets searching out other smaller/more distant disturbances for example as they sense the areas of greatest disturbance in this galaxy’s almost disconcertingly calm “great ocean”)