The Highlanders announced yesterday that Thorn, the 59-test All Black lock, has signed with the franchise for next season.
Thorn said yesterday, from Japan, the opportunity to join the Highlanders became more attractive the more he thought about it.
"It means I can come back to where things kicked off for me - where I first played rugby as a 6-year-old and then across the hills at Taieri Rugby Club where my father played, my brother played and my uncle played," Thorn said.
"That is pretty cool for me. We saw it as a fun opportunity to come back and contribute to the Highlanders."
Thorn is playing for Fukuoka Sanix Blues in Japan which has connections with Highlanders coach Jamie Joseph.
Joseph helped coach the side last month and talked to Thorn about coming to play for the Highlanders.
"He talked about Otago and what he was doing and it is where I am from ... he got my interest. Me and my wife talked about it for a couple of nights and thought it sounded like a good challenge. I still want to play top-level rugby. I still feel pretty good and I still want to play Super rugby which is the toughest rugby competition in the world."
The initial thoughts had been to head to Europe after he spent a successful three-month spell with the Leinster club in Ireland earlier this year, and ended up winning the Heineken Cup.
Joseph though won him over.
"He just impressed me straight away. He likes being up front and believes in hard work. He's a pretty intelligent guy as well. I just had a good feel for the guy and got on well with him straight away."
Thorn played rugby in New Zealand as a youngster and then moved with his family to Australia before he was 10. He played rugby league in Australia and represented the Brisbane Broncos, Queensland and Australia.
He played 92 times for the Crusaders and has played more than 400 first-class matches of both league and union.
Despite turning 38 in February Thorn said he still felt in good nick.
"The body is good. I don't feel any different than three or five years ago. I have not missed a game since the World Cup both in Japan and Ireland."
Thorn said after playing in Ireland he went around Europe for five to six weeks and that did a lot of good for both body and mind. In Japan you could maintain your body better because the rugby was not as intense as New Zealand, he said.
"So it was sort of like having a proper pre-season really."
Thorn's signing is the latest in a string of big captures for the franchise with All Blacks Tony Woodcock and Ma'a Nonu also heading south.
"It was cool to have Tony Woodcock coming down there and there are a lot of guys that I played with. Ma'a and I started out in the All Blacks together in 2003 and I have had a lot to do with him. I helped him working with the young All Blacks and stuff. Now we've got an opportunity to see him down there."
Thorn, wife Mary-Ann and their four kids will relocate to Dunedin early in the new year.
Although an exact date has yet to be confirmed Thorn expects to join up with his new side in early February.
"Where I go my family goes. That has always been the way with me. Some guys up here leave them back home but for me they have always been with me. We are just pretty tight."
