I just got hired at gamestop in Oregon and I start work the day after tomorrow, but they didn't tell me what my attire would be, has anyone worked at gamestop before or knows what the attire for game advisor?

If they didn't mention it, they expect neat clean shirt, pants, and shoes (possibly clean sneaks). Not tees, jeans, and dirty holey sneaks. Once you are working, they might tell you that it's OK to dress down more. But even in a gaming store, not all your customers will be grungy kids.

Call the person that hired you and ask.