The Gaming Third-Eye is another way of saying a gamer has evolved in to its later stages. Someone who has opened the Gaming Third-Eye usually has 12 hours game sessions with short break intervals and is usually only found in older people/ people who don't have school because they have nothing better to do they game for a long period of time.
Person 1: dude have you seen Chris lately?
Person 2: No man, he opened his Gaming Third-Eye