"RAAM's Shadow"'s greatest strength is its premise. A prequel set in the hours following Emergence Day, the first piece of campaign DLC for Gears of War 3 hints at what Ilima City looked like before it was destroyed, both by the Locust and the COG's scorched-earth reaction. There's a sense of melancholy that permeates the three-hour campaign as you run through a city you know will soon be ruined, accompanied by characters who will soon be dead.
There's a certain elegance in the way the Gears series (and sci-fi in general) can extract so much meaning out of such broad strokes. Games like Gears of War work because the audience instinctively realizes that war is terrifying; "RAAM's Shadow" works because it situates itself deftly into a world-mythology already primed for despair and hopelessness.
The problem for Gears, though, is the broader themes never get distilled into specific characters or narrative action. The soldiers of Zeta squad are rough-hewn archetypes, and their orders are simply to save any humans and kill any Locust they find.