Should you allow kids play video games at the age of four to six

Video games develop hand/eye coordination and impart considerable knowledge. For that reason they are not, in moderation, harmful for small children. The key is moderation, and to stick to learning games that are based in the real world, instead of fantasy games.
Violence should be avoided at all costs. There is considerable research indicating that children exposed to the impersonal and penalty-free violence of gaming develop skewed perceptions about the relationship of violence to everyday life.