One of the great delights of being a purely surface-level Warhammer 40K enjoyer is that around every corner there's always some new, human-made horror to discover. The other day, for instance, I learned about the Exterminatus, a giant, Galactic Empire-inspired space gun that blows up planets when all other options - Space Marines, Grey Knights, Titans, Orbital Bombardments, et cetera - have been exhausted.
Warhammer 40,000: Chaos Gate - Daemonhunters, a new turn-based tactics game in the vein of XCOM, coming 5th May, will let you fire it, and is actually the first 40K game to feature it as a proper mechanic.
The central premise here is that a plague called the Bloom has broken out across a series of planets, thanks to Nurgle, the Chaos "Plague Lord" whose MO is being gross on a large scale. It's your job, commanding a squad of Grey Knights - mysterious, elite Space Marines - to save as many planets as possible and ultimately stop the spread.