The game, The Walking Dead, is rated 'mature' by the US's  Entertainment Software Rating Board, meaning it should not be played by those under 17 years of age. 

 

"I had a deep personal desire to use this type of teaching because I believe it leads to better learning and greater engagement among students," Tobias Staaby, a teacher at Bergen's Nordahl Grieg High School, told Norway's state broadcaster NRK. 

 

"In the first hour I walk through the points in the curriculum, then we start to play and every time we come to an ethical dilemma, we put the game on pause," he explained. 

 

"When they have finished the discussion, every student votes anonymously on a web-based application called Kahoot! about what they would do." 

 

Staaby said he has been surprised by how positive the reaction from both students and their parents had been. 

 

"I thought I would get angry phone calls from mothers and fathers," he said. "But so far I haven't got any."

 

Taking ambiguous moral decisions is a central part of the game, which is made by California's Telltale Games, with players encouraged to see the zombies as feeling soulful creatures. 

 

Unlike most other adventure games, the choices players make are not scored as "good" or "evil" but instead influence the way computer-generated characters respond to the player. 

 

"Killing one actually means something," the New York Times explained in its review in 2012.

 

"Taking an ax to the reanimated corpse of a character’s brother in the streets of Macon, or deciding whether to give a gun to a woman who was bitten and now wants to kill herself before she is reborn — these moments have more sadness and subtlety in them than other games muster in 40 hours," the paper wrote.