Varies: There is no specific dangerous heart rate during exercise. How fast your heart beats with exercise depends on a number of factors, especially your conditioning. If you are healthy, a heart reate in the 170's or even higher may be ok and tolerated.
Motion sickness caused by video games, sometimes called simulator sickness, is caused when there is a disconnect between what your eyes are seeing and what your body is feeling.
Another common cause of nausea is motion sickness. Lying down when the nausea begins often helps people who have motion sickness. If you're motion sick, try to breathe fresh air (i.e., via an opened window), and avoid reading or any activity that forces you to focus on something closely while in motion.