The 15-year-old Model schoolboy stalled a branch of Barclays bank in Breck Road, Liverpool, on September 20 and successfully made off with more than £2,000.
The boy who cannot be identified for legal reasons, acted as if he was in a "real-life video game" when he carried out the raid.
But he was turned over to the police by his mother who was stunned to find a stash of cash, stained with dye, and a fake firearm in his bedroom.
The case has been sent to Liverpool Crown Court for sentence.
According to Press Association release UK, district Judge Ian Lomax said: “The case is a very serious matter. It's an armed robbery but not in the conventional sense most people would recognise.
"It's a bizarre, surreal case of a young man almost acting like a real-life action video game. Nevertheless it was a robbery."
The court heard that the boy was a "model pupil" at school and was not known for mischievous behaviours but envious of other people's material possessions.
Mr Lomax said his crime was "motivated by greed and immaturity" and by "whatever influences" he had been under in recent time.
The judge said those influences may include "another pupil or something you have been watching or playing".
The boy, who pleaded guilty to two counts of robbery and one count of possessing an imitation firearm with intent to cause fear of violence, was granted conditional bail and is due to be sentenced at Liverpool Crown Court later today.