You can find everything from science fiction to adventure games and collectibles.
"Pretty much the whole environment just keeps drawing us back. Being immersed in this kind of atmosphere -- it's just awesome, it's really fun," gamers Kaytie Steckler and Michael Massey explained.
A big part of Gen Con is the costumes, and because of those costumes, people-watching has become a popular event around the convention center. Characters from the comics to the big screen can be seen walking the streets of downtown.
Gen Con runs through Sunday. A badge that will get you in all four days costs $80 and a one-day badge is $50.
Sunday is Family Fun Day and a family of four can get in for $30.