The 27-year-old paid credit to his fellow teammates, coaches, clubs and everyone who had supported him.
"I would like to thank the Waihi community and my family and friends.
"The support has been unreal. It's been awesome."
Ranga says he will just chill now but will continue to keep up his training in the lead-up to 2019.
"I'll be donning the Waihi Athletic Rugby jersey again and I want to get back into the Swampfoxes. I'll just have to see how my body holds up."
Waihi Athletic Rugby Club coach Bryce Bevin says Ranga is "a very complete footballer who has skills on attack and defence".
He had physical prowess on the field and was fast and agile.
Ranga reminded him of rugby legend and former All Black great Ian Kirkpatrick.
"The try Ranga scored in the final of our club rugby reminded me of how brilliant he actually is. He ran about 60m to score a try just like Ian Kirkpatrick did for the All Blacks in 1971 at Lancaster Park."
Meanwhile Waihi Athletic Rugby Club president Mark Ryan says Ranga is the kingpin of the senior team and a natural born leader.
His performances in helping the Waihi Athletic Rugby Club and Thames Valley Swampfoxes take out consecutive titles in their divisions for the first time has been outstanding, he says.
"He spent a couple of years playing the Bay and he has really come back a new man. We are so glad to have him. He leads from the front and he is a born leader. His talents and ball skills are phenomenal for a big guy.
"Brett's commitment to the game and his competitive nature really puts him exactly where he is now."
Watching Ranga being presented with the Mitre 10 Heartland Championship Player of the Year award by All Black captain Kieran Read at the 2018 ASB Rugby Awards was fantastic, Ryan says.
Thames Valley Swampfoxes chief executive Edmond Leahy says Ranga has been an outstanding player and captain for the 2018 campaign.
"He is not only a great leader but an outstanding individual player."
He says the Swampfoxes got off to a poor start but improved steadily.
"We picked up after that first game and we built momentum to the final. Winning the final was exciting and history making."