Well It depends what youre playing really. If you play doom 3 like 12 hours a day, you're bound to be worse off then playin mario all this time.Videogames can icrease your reaction speed, and other things, but playing for twelve hours ins't healthy. It mentally exhausts you, and can maek you quite short tempered I imagine.
However my friends and I are having a mario marathon . We are playing as many mario games through in a span of 24 hours, as we can. I imagine we will get too Mario 64, or Sunshine
PS:Playing PC Games really Fed up my eye sight. Its really bad now. I need new contacts. Im like -3 on each eye.