Torchlight II also saw a 40% spike in sales the day Diablo 3 was released.
Diablo III was originally intended to be an MMO, according to Runic boss and ex-Blizzard staffer Max Schaefer.
"When I was working at Blizzard a million years ago we were working on Diablo 3 and it was an MMO," Schaefer told I.Eat.Games.
"We were going to do the Diablo version of World of Warcraft. Blizzard obviously changed that pretty quickly, so we left to start Flagship Studios and we brought in a lot of the guys, so they rebooted with their own team."
Flagship Studios was founded in 2003 by Bill Roper, along with Max Schaefer, Erich Schaefer, and David Brevik - the original creators of Diablo. After the disappointing Hellgate: London, the studio went bust in 2008, with Max and Erich Schaefer then becoming part of the team at Runic Games, developers of Torchlight and the upcoming Torchlight II - both similar games to Diablo.
When asked how Diablo 3's success may have helped or hindered the launch of Torchlight II, Schaefer said that the game's pre-sales shot up 40 per cent on the day Diablo III came out.
"We're doing pre-sales on steam, and the day Diablo 3 release they shot up 40% and have stayed up. They're bringing in lots of people into this genre, and people are becoming aware of what we're doing through them."
"We're kind of piggybacking on their marketing," he added.
Schaefer also joked that he'd like to see Torchlight II get its own version of the dreaded Error 37 problem. "What that Error 37 really means is you have 6 million people pounding on your servers, so we want our Error 37 equivalent."
Torchlight II is currently scheduled to be released this summer.