Chair Entertainment Group today announced that Undertow, an underwater action-shooter powered by the Unreal Engine 3, has launched for Xbox LIVE Arcade. Undertow features two multiplayer modes for up to 16 players, and a robust 15-level single player and co-op campaign. Players navigate the stormy seas as one of four unique, upgradeable unit types ranging in ability from the fast and agile to the large and powerful. Players then earn points for adding upgrades by killing enemies, completing objectives, and taking checkpoints. Check full story for details.