The Unreal Engine 3-powered, "Metroidvania"-styled side-scroller Shadow Complex broke Xbox Live week-one sales records with 200,000 units sold, Epic Games and developer Chair said Monday. The companies, along with Microsoft, said the game is the most-downloaded single-player game in Xbox Live Arcade history for the first week. Shadow Complex, released on August 19, is Chair's sophomore effort on Xbox Live, having released Undertow in 2007 -- also powered by Unreal. Shadow Complex "exceeded sales expectations," according to a statement. It also garnered strong reviews from video game press outlets. Gears of War house Epic Games acquired Chair Entertainment Group in May 2008. The two companies worked together closely on the development of Shadow Complex, a game inspired by series like Super Metroid and Castlevania. Chair's Donald Mustard explained at E3 2009, prior to the game's release, why the studio pursued the 2D exploration gameplay in a time when open-world 3D gaming is so prevalent. "I think we come back to 2D partly because of nostalgia, but I also think that this design works so well with exploration, where you're kind of peeling back these onion layers of the game," he said. Mustard added, "I don't know how well it really works in 3D. I think there's something very particular about this design that's so fun and compelling that it just works a lot better with this camera perspective. This can be immersive in its own, different, unique way." Scott Austin, Microsoft's director of digitally-distributed games, called the game a "capstone title of the second annual Summer of Arcade program."