If they hire you, it'll be a pretty cake job. File games, clean the store, sell product, close shop. Rinse and repeat. However, I wouldn't recommend working at Game Stop right off the bat, even though you're probably a game enthusiast and enjoy the environment. My first job was a bagger at a nearby Publix and that was probably one of the best jobs I had. Fast advancement, weekly pay, decent work hours (especially for persons under 18), and hot moms and their daughters from sun-up to sun-down.
Game Stop, being usually small storefronts, will generally have a small staff and a real low turnover rate. The opportunity for advancement is probably very low, the hours will be super-weak, and the novelty of working where most everybody within your age range goes to shop and (mostly) loiter will wear off really fast.