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.
Motion sickness is due to irritation of a portion of the inner ear called the labyrinth. The symptoms of motion sickness include nausea, vomiting, and vertigo. Other common signs of motion sickness are sweating and a general feeling of discomfort and not feeling well (malaise). Symptoms usually stop when the motion that causes it ceases.