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,” …