Enraged developers are threatening to boycott one of the world's most popular game engines. But what has Unity done to spark such huge backlash?

Unity proclaimed that on Jan. 1 it would be implementing a pay-per-download pricing model to charge developers a flat fee any time someone installs a video game utilizing Unity software.

After Unity on Tuesday announced a new pricing plan for developers using its engine, a wave of anger, fear and confusion spread across the global game development community.

Video game engine maker Unity has apologised after a furious response to its proposed new pricing plan. The company behind the development tool said it wanted to charge studios every time a game ...