While writing his "Stay Awhile and Listen" book about the history of Blizzard, David Craddock interviewed numerous former employees who revealed – among other things – that the company experimented for several years with a Diablo III game set in in space.
"After [Diablo II], the company split into separate teams: a Diablo team, and a 'We love Diablo but it's time to try something new' team," he explained. "They started and scrapped more than half a dozen ideas before a few team members suggested making a Diablo clone, but set on a space opera stage."
The team worked on the space-diablo game for years, but they couldn’t come up with a name better than "Starblo."
"Like Diablo II, Starblo would take place over several acts, but rather than journey across a single world, players would board their customizable spaceship and travel to new planets, killing and looting the space creatures they found there. By the time Dave Brevik and the Schaefers left Blizzard North in summer 2003, the Starblo team had produced a few playable builds of the game, but still hadn't come up with a proper name."