Police believe the attack, in Clydebank, Scotland, was influenced by the teenager’s use of violent video games.
He had only known his 14-year-old victim for a few months after they met online while playing Xbox game Gears of War 3.
The 18-rated game, which contains ‘strong bloody violence’, rewards players for devising ways of murdering their opponents.
Brian Docherty, chairman of the Scottish Police Federation, said: ‘These games are rated 18 and shouldn’t be played by children of this young age – but online gaming may be outside their parents’ knowledge. We need to look again at what we can do to stop this.’
The High Court in Glasgow heard the boys had a falling-out, which resulted in the victim being slashed.
Then, in a scene reminiscent of violent video games – the accused sneered at his victim: ‘Don’t die,’ before calmly walking off. The accused, who cannot be named for legal reasons, admitted assault.
The victim is now traumatised and his attacker – already a father – faces being locked up when returns to the dock later this month.
Prosecutor Andrew Brown, QC, told the court: ‘The reporting officer was of the opinion that the violent video games played online by the accused may have been a factor in his conduct.’
The boys met while playing Gears of War 3 online around Christmas 2011.
They later met in person and the court heard there was no animosity between the pair until a month before the slashing.
Mr Brown said: ‘The pair had fall-outs online amounting to name-calling via the messaging system used in the game.’
On April 14 last year, the day of the attack, the victim met some friends and the group later encountered the accused at a local shop.
Later that night, the victim and another boy were going to a house when they saw the accused.
The accused grabbed the 14-year-old then struck him across the throat with a knife.
The victim told paramedics a boy had ‘slit his throat in an argument about Xbox games’.
He suffered a wound so deep it exposed his windpipe and required 20 staples following surgery.
The court was told the victim – now 15 – has refused to speak about what happened to him and has had difficulty sleeping.
A spokesman for Microsoft, which publishes Gears of War 3, said: ‘We have some of the most robust parental control systems to empower parents to decide how their children play and communicate.
We have the greatest sympathy for the victim and his family.
