1. A rehabilitation system for stroke victims comprising: a depth sensing camera positioned to view a workspace into which a patient's hands may be located, the camera providing a. resolution allowing identification of actual hand and finger positions of the patient's hands; a display system viewable by the patient; an electronic computer executing a stored program in receiving information from the depth sensing camera to: (a) display on the display system a representation of a virtual space holding at least one virtual object having predefined dimensions and spatial location in the virtual space; (b) display a representation of at least one hand of the patient depicting a location of the hand and position of the hand and fingers in the virtual space according to a predefined mapping between actual space and virtual space; (c) monitor a virtual manipulation of the virtual object by the patient's hand to provide a metric indicating a performance level by the patient in manipulation of the virtual object; and (d) change a difficulty of a rehabilitation task requiring virtual manipulation of the virtual object by the patient's hand.