In Red Faction: Armageddon, Darius Mason does indeed open up an ancient shaft on the surface of Mars, awakening a long-dormant alien race from its slumber to kill his fellow colonists in droves, but it's not his fault. He was tricked.
It's all Adam Hale's fault, though technically the blame lies on Darius' grandfather Alec Mason from Red Faction: Guerrilla. See, Alec killed Adam Hale's dad, a captain in the Earth Defense Force, and Adam's been holding a grudge for quite some time. That's why he tricks Darius into cracking open the ancient resting place of the gigantic insects you'll be fighting when Red Faction: Armageddon hits the Xbox 360, PC and PlayStation 3 in early June.
He could have just opened it himself, I suppose, but you don't go around wearing evil makeup if your plans are that straightforward.