The attacked happened at about 1 a.m. on Sunday, Aug. 3, 2014, on York Street just south of Queen Street West.
Police say the victim stepped out of a taxi and was immediately assaulted by six men who later fled on foot. Some of the suspects headed westbound on Richmond Street, others went west on Queen toward University Avenue. Three of the men were spotted getting into a taxi at University Avenue, heading northbound.
The suspects, aged 18 to 25, were captured on security cameras. They are described as five black men and one white man.
The footage and images police released on Friday are not new. Police are hoping that re-releasing them will jog someone's memory.
"This family needs closure," said Det.-Sgt. Paul Rinkoff.
"Several tips came in," said Rinkoff. "Unfortunately the investigation to date has not led to any arrests."
The victim was in a coma for one month after the assault and has undergone several surgeries that police say saved his life. He is under constant medical supervision and police say while his condition has improved somewhat, he will likely never enjoy the same quality of life.
Police say they don't know what prompted the attack. The victim's family do not want him identified publicly.