Elderly people can suffer some degree of decline in their cognitive capacities, usually including different symptoms (decreased problem solving capacity, decreased ability to reason and to maintain focus, forgetfulness, etc.). Cognitive stimulation has been shown to decrease the rate of intellectual decay and potentially reverse age-related cognitive decline. Serious games provide new training opportunities to improve the decrease in selected social, sensory-motor, cognitive and emotional functions of elderly people. This paper details the objectives of the VIRTRA-EL web platform, which has been designed to evaluate and train cognitive skills to elderly users by means of serious games using the personal computer or tablet devices. Additionally, we present a serious game based on interactive 3D environments, which has been designed with the aim of helping to train memory, attention, planning and reasoning.