He is 15, a model student and comes from a well-to-do family.
The boy, who was not named, burst into a branch of Barclays bank in Liverpool last week, pointed a fake handgun and terrified cashiers while asking for cash.
He shouted: "I'm not ******* messing around - I've just got out of prison after five years" before fleeing with £2,200 (S$4,425).
A district judge said that the teen may have been influenced by something he had "been watching or playing", the Mail Online reported.
Said Judge Ian Lomax: "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 judge said the case was very unusual because the boy had never been in trouble with the police before.
Studies show that ultra-violent games can lead to copycat behaviour among teenagers.
Grand Theft Auto V, the latest game in the notorious series, was released last week to massive controversy.