Maybe a strategy game about the war between the Sarkists and the early COTBG, in the vein of Warcraft or Starcraft (Sarkists as the Zerg, COTBG as the Protoss/Terrans, with more the aesthetic of the former
Sarkic gameplay would specialize more in producing cheaper units (such as Flesh That Hates infectees and human cultists) faster (with some exceptions) and involve buildings like a slave pen (resource generation) and a Fleshcrafting temple (construction).
The Church would have Colossi (like SCP 2406) as powerful, expensive, late-game units, and structures like mines (resource generation) and War Foundries (Construction).
Both sides would probably have Champions/Heroes, such as Karcists for the Sarkic side.
For some reason, I inmagine the Colossus pilot's dialouge would be full of Mecha anime refferences, such as "Mustn't run away" when the collossus takes major damage, or "PIERCE THE HEAVENS!" when killing a powerful enemy unit.