Based on Warhammer 40,000, deep under the central desert of Kronus, a vast honeycomb of skull-lined tunnels and funeral chambers house the awakening Necron menace. Eons ago, these were the boulevards and squares of a great necropolis built to house the bones of the races who had fallen to the Necrons, and ultimately were where the Necrons themselves retire to spend eternity. Over millions of years, sand and rock had covered it all until ill-fated excavations awoke the deathless.
Sad Spires comes in two flavors - 2 & 4 player versions. It also has a working tunnel system curtesy of fuggles for quick redeployment of your troops. Should work on Dark Crusade as well as Soulstorm.
A more greyish map with a simple layout. You can use the tunnels for advanced mobility. Readme says it should work on Dark Crusade, too. Just can't remember after such a long time but I guess I can trust my old self.