Control schemes are central to the user experience in video games as they determine the quality of a user's interaction with the game world. Since the 1990's, desktop 3D games have adopted the "mouselook" scheme, in which the mouse simultaneously rotates the camera view, aims and steers the avatar. However, virtual reality games do not yet have a standard control scheme and require a different approach in order to integrate input from the head-mounted display, an additional input device not present in desktop 3D games. To address this gap, we conducted two mixed-methods studies to evaluate the usability of control schemes for controller-based VR games in the FPS genre. User study 1 showed that "coupled" control schemes were most usable. Study 2 showed that both the coupled and "decoupled" schemes were usable, although some users found the decoupled scheme disorienting.