The students at Hersby High School in Stockholm's Lidingö had written names on slips of paper, with the aim of the game to hunt whoever's name was pulled.
One student, a 17-year-old boy, pulled the short straw and was to be hunted by his classmates.
But events took a turn for the worse when he took a steep and unexpected fall to avoid capture, reported the Aftonbladet newspaper.
One of the students estimated that the boy fell "four to five metres", and police were called to the scene shortly after.
"The person was conscious," Ulf Lindgren of the Stockholm police told the paper.
"From what we've heard, this is nothing other than a pure accident. The person has been taken with the ambulance helicopter to the Karolinksa Hospital."
Hunger Games, a popular science fiction film series based on the books by American Suzanne Collins, sees children fighting each other to the death live on national television.