## 1 Introduction  
Falls become a significant problem in the aging population. Falls are prominent factors of accidental or unintentional injuries implied by external causes [1, 2]. The incidence of falls amongst elderly people, according to the World Health Organization, varies from 28-35% of individuals aged 65 and over, increasing to 32-42% for those over 70 years of age [1]. Falls result in the fear of falling, loss of independence, institutionalization, and eventually death [3]. Strategies to prevent falls are crucial to the well-being of the elderly population, and rehabilitation plays an important role among them. Standard rehabilitation protocol focused on the prevention of falls comprises kines-sidotherapy (exercises) and education. Exercises should include training of body balance, coordination, gait, changing the body position, minimizing the possibility of an injury during a fall, and techniques of getting up properly after a fall. Exercises are effective in reducing the risk of falling [4]. Advances in medical technology resulted in the popularization of computer-assisted interventions in rehabilitation treatment. New technologies in rehabilitation comprise of a variety of biofeedback implementations into hardware platforms, motion capture systems augmented by biofeedback, augmented reality (AR) systems, and virtual reality (VR) systems. Technological appliances vary from adoptions of popular gaming hardware platforms to specialized systems with dedicated hardware and software. Software protocols, presuming adequate hardware implementation, can be integrated into a complete computer game, which may result in better adherence. An application of virtual reality techniques in exergames can result in even better immersion into \"digital worlds\" and leads to the proposal of reframing the interpretation of virtual reality into two components: virtual reality experience (VRE) and virtual reality systems (VRS) [5]. The virtual reality experience comprises at least four interrelated contributors: immersion, interaction, sensorimotor contingencies, and illusions. Virtual reality systems refer to physical solutions to generate virtual reality experience. Among the contributors of VRE, the effectiveness of interaction bonds them all together, eventually resulting in illusion. The interaction in VRE starts with visual exploration of the space, which can be provided by simple display, stereoscopic display, head-mounted display (HMD) with head tracker or more advanced motion-tracking systems. The experience can be further augmented by spatial sound effects, haptic data gloves etc. Next level interaction can be provided by means of brain and other bodily inputs, leading to so-called neurogames, which use brain or muscle signals to control basic interaction features [5]. Such implementations require the application of brain-computer interfaces (BCI), which are capable to non-invasively collect and further interpret collected brain signals. Regarding the input concepts, one has to distinguish augmented reality, which combines virtual and real world, and virtual reality, which substitutes real world with multiple sensorial channels, leading to more or less complete artificial stimulation, creating non-immersive or immersive VR. BCIs can be used both in AR and VR applications [6; 7]. In view of rapid technology advancements, solutions in the form of small brain implants are inevitably coming, forerun by experimental devices like scalable high-bandwidth brain-machine interface system [8]. Exergames are defined as the activity of playing video games that involve physical exertion. Interventions making use of exergames have a favorable effect on both motor and cognitive functions [9; 10]. Exergames have promised a form of intervention, which improves physical function in older adults, while endangering few adverse effects [11]. Exergaming, as an interactive, entertaining and engaging form of exercise, may help to overcome traditional exercise barriers and improve adherence in the case of older adults.