Andy Darley, who joined in the internet game Perplex City in December 2005, finally dug up the hidden treasure – known as the Receda Cube – from the wood near Corby last week.
Web designer Mr Darley, 38, beat 50,000 competitors from 92 different countries to be declared the winner, after solving a series of puzzle cards designed to help players piece together the location of the treasure.
Perplex City is a alternative reality game that takes place both on and offline, allowing players to interact with each other, as well as with fictional characters from the world of Perplex City.
Players across the globe spent £1 million on puzzle cards, which gave cryptic clues pointing to the treasure.
Virtual Indiana Joneses then used them in their quest to piece together the whereabouts of the Cube.
He said: "The cube could have been hidden anywhere in the world, so I never thought I would be part of the end game."
A joint effort by the community of players to solve the clues resulted in the location of the Receda Cube being narrowed down to somewhere on the Jurassic Way, an 80-mile footpath in Northamptonshire.
Mr Darley, who has some archaeology training, said: "The moment I looked on the information board at Wakerley Great Wood I recognised some co-ordinates on there, so I knew I was on the right track -– but it still took four visits.
"When I eventually got to the right spot I saw that the earth there had been dug up before so I knew I'd found it.
"When I pulled the cube out of the ground it was a very, very strange moment.
"I am absolutely gobsmacked."
Andy, from Hertfordshire, and his girlfriend are now looking forward to spending the prize money on a house.
He said: "We were already house-hunting and we thought we were going to have to borrow about £100,000, so this works out very nicely."
Michael Smith, CEO of game's producers Mind Candy, said: "Andy's finally cracked a puzzle that we've spent years developing and that thousands of people worldwide have been slaving over for months.
"He fully deserves his reward."
The discovery of Receda Cube marks the end of season one of Perplex City.
Season two will launch in spring this year.