A person that no matter what happens he will always be thinking or playing video games, you dont need to be male or fat or even have glasses and be bullied, a gamer is a gamer, they care only about videogames and they normally prefer them to people, they have less friends and spend their free time sweating kills.
(they get very excited when they kill someone)
(new guy)- who is that in the computer room on his own?
(student)- oh, he is a real gamer.
(real gamer)- YESSSS, I GOT A KILL BOIIIIS!!!!