Forgotten Title Cultivation story but mc made illusion training with setting of WH40k

[RobotRatz666]

a cultivation story that I remember nothing about Only that he created these illusions training rooms with different scenarios one being warhammer 40k. Mc has younger brother that is a bro-con? what I remember is that in a side story showing the future following the brother in his search for the Mc that disappeared. He ends up on a planet following clues about mc that has aspects of warhammer 40k / there was space marines. The author was alluding that the training rooms were not just illusions but full on worlds that were created.

mc might have a harem, can’t remember.

this story could be on this site, royalroad, or potentially webnovel though I don’t think it is on webnovel but …

thanks in advance

 

[Kenjona]

If you find it let me know, sounds intriguing.