A man repeatedly assaulted, twice while unconscious, was "effectively helpless against the onslaught" of the sudden and vicious pokie room attack, a court has heard.
"It was an innocuous and thoroughly trivial argument that led to a violent altercation," a prosecutor said on Thursday.
Joshua David Slarke leaned over in his ACT Magistrates Court seat and kept his head down throughout his sentencing proceedings.
The 28-year-old man did not look up to watch CCTV footage of his drunken assault, which took place on December 1 of last year during his work Christmas party.
Slarke previously pleaded guilty to assault occasioning actual bodily harm, admitting repeatedly punching the victim.
The attacker, who has spent no time in custody for his crime, walked away with a fully suspended three-month jail sentence, six-month good behaviour order, and 50 hours of community service.
According to court documents, the victim told Slarke to "pull your head in mate" when he believed the offender was bullying a colleague at the Gungahlin Lakes Golf and Community Club in Nicholls.
Slarke grabbed the victim's collar during an ensuing argument and, after being separated, the pair agreed to "take the argument outside".
However, when the victim remained in his seat, Slarke returned to the pokie machine room, pushed the other man backwards and struck him in the head twice.
Special magistrate Rebecca Christensen described the sustained assault as occurring "without warning" after a "rapid advance".
Holding the victim by the collar, Slarke punched the man, who had now fallen backwards with his shirt pulled over his head, two more times in the jaw "in an uppercut motion".
But it was Slarke's next two punches that would render the victim unconscious for 50 seconds. CCTV shows the motionless victim slumping down in his seat.
"The defendant then punched [the victim] another two times in the same manner to the right side of the head," court documents said.
Slarke immediately walked out and into the venue's outdoor area before fleeing by jumping a fence. His victim was taken to hospital and treated for lacerations, bruising and abrasions.
Defence Lawyer Tim Sharman told the court the assault was very serious and had followed a "misinterpretation".
"It's one of those cases where it's acknowledged by pure luck alone the injuries aren't as serious as they may have been," he said.
Mr Sharman said his client had expressed remorse and accepted responsibility for behaviour the court heard was uncharacteristic.
The magistrate said challenging life and work factors were "seemingly playing on [Slarke's] mind" at the time of the alcohol-fuelled attack.
"But that does little to justify the vicious nature of the assault he committed on a fellow community member," Ms Christensen said.
Slarke's suspended sentence is set to end in November.
