Video games genres can be classified according to scenario, narrative structure, mechanics, dynamics, interactions between the player and the game, and internet connection, as games can be played on-line via internet in real-time or off-line. With main respect to interactions between the player and the game, a simple classification includes traditional, strategy, simulation and action video games. Several links were found between playing certain video games and enhancement in some aspects of cognitive functioning such as divided attention, sustained attention, capacity of visual attention, visual working memory capacity, learning foreign language or second language, with different games enhancing different aspects of cognition. Most individuals play video games unproblematically, however, uncontrolled, excessive playing and its negative consequences require appropriate diagnosis. Gaming disorder is characterized by impaired control over gaming, increasing priority given to gaming and continuation or escalation of gaming despite the occurrence of negative consequences, associated with persistent or recurrent course over a period of at least 12 months and resultant significant interference with personal functioning. Studies indicate that gaming disorder is linked in some brain areas with underlying neurobiological changes such as increased glucose metabolism, hyperactivation or hypoactivation, lower resting-state static functional connectivity, reductions in synaptic density, decreased levels of dopamine D2 receptor availability, decreased gray matter volume, gray matter density, cortical thickness and cortical volume. Various psychological factors were found to be involved in gaming disorder, including motivations linked to reward-seeking, fascination with an alternative world and alternative self-concept, low self-esteem, impulsivity, dysregulation of reward system, and escapism.