Grimdark Warhammer 40,000 album cover, ultra-detailed realistic sci-fi style. Center composition: a colossal Iron Warriors siege engine — a massive tracked artillery platform fused with gothic industrial architecture, covered in black-and-yellow hazard stripes, iron plates, exposed cables and rivets. The machine dominates the scene like a moving fortress. No visible heroism: Space Marines of the Iron Warriors appear only as small, disciplined figures around the machine — faceless, identical, methodical, like parts of one system. Environment: a devastated fortress world during a prolonged siege. Broken walls, collapsed bastions, cratered ground, skeletal remains of towers and trenches. Heavy smoke rolls across the battlefield, ash falls like snow. Sky: dark iron clouds torn by distant explosions and artillery flashes, no bright light, no hope. Lighting: cold, industrial, low-key lighting with harsh highlights on metal surfaces, deep shadows everywhere else. Color palette: gunmetal grey, soot black, muted brass, dirty yellow hazard markings, faint red glows from furnaces and weapon ports. Mood: inevitability, endurance, mechanical war without emotion. Style: cinematic grimdark realism, industrial sci-fi, Warhammer 40K aesthetic. No text, no logos, no symbols. Aspect ratio: square (album cover).