What happened to my brain?!!?

Did you get dizzy before or after you stood up? if it was as you were standing, it probably happened because you stood up to quick, it happens from time to time because the blood rushes down causing lack of oxygen in the brain, making you dizzy. If it happens frequently though see your doctor, i mean like twice a day or something

Sometimes staring at moving shapes and colors too long will give you the feeling of being high. Most of the time your vision is just distorted, but some people also can feel dizzy. (Like you did.) I recommend that you take short breaks from playing video games every hour you are playing. If it continues to worsen, got see a doctor cause it might be linked to seizures. (But that's probably not the case.)

Dehydrated?

Do you get enough sleep? If not, please do. A good rest may be all you need. If this happens regularly then you must see a doctor

Maybe you were playing for too long