A disgruntled indie developer has had his game pulled from Steam after he issued a death threat to Valve CEO Gabe Newell over Twitter.

Paranautical Activity developer Mike Maulbeck said he released the final version of his PC game to Steam today, but the game's Steam page still suggested it was in Early Access. The developer told Polygon he believed this would "greatly cripple sales and confuse customers."

"This being a project I spent years of my life on, I was very frustrated by this mistake [Valve] made, so I tweeted a series of tweets calling them incompetent that eventually ended in me saying 'I swear I'm gonna fucking kill gabe' or something," Maulbeck said.

Maulbeck said it was clear he didn't mean what he said, and he understood that what he said was "totally unacceptable". He said it was "driven entirely by the heat of frustration I was feeling at the time."

Maulbeck went on to describe Steam as a "awful fucking monopoly," and allegedly said in a tweet that has since been deleted, "I am going to kill gabe newell [sic]. He is going to die."

Valve has responded by pulling Paranautical Activity from Steam and closing the developer's Steam administrator account.

Valve's Doug Lombardi confirmed that Paranautical Activity had been removed from Steam due to Maulbeck's public outburst.

"Yes, we have removed the game's sales page and ceased relations with the developer after he threatened to kill one of our employees," said Lombardi.

The game is available on other PC digital distribution platforms such as Desura, however Maulbeck told Polygon that the game had only sold 12 copies on non-Steam platforms.