PC games giant Valve is the subject of a class-action lawsuit claiming that its Steam platform is a monopoly.

The case was filed on Tuesday, April 27th in Washington's Western District Court led by developer Wolfire Games, which claims that around 75 per cent of PC games spending is done on Steam, netting Valve "over $6 billion" in revenue in a given year from its cut.

The suit claims that Valve abuses its position in the market to stifle competition, in part due to price parity provision enforced in its Steam Key system. This means that developers and publishers have to offer the best price on Steam, making it tough for other platforms using Steam Keys to compete. The lawsuit claims that this is the reason that Valve has been able to maintain its 30 per cent cut of sales all this time.

"Valve’s scheme imposes a massive tax on the PC Desktop Gaming industry," the case claims.

"Game publishers are forced to use the Steam Store and give Valve 30% of nearly every sale if they want to gain access to the Steam Gaming Platform—access they need in order to sell their games. In order to afford Valve’s 30% commission, game publishers must raise their prices to consumers and can afford to invest fewer resources in innovation and creation. Gamers are injured by paying higher retail prices caused by Valve’s high commissions. Competition, output, and innovation are suppressed, in ways that can never be fully redressed by damages alone. Thus, in addition to damages, injunctive relief removing Valve’s anticompetitive provisions is necessary to bring competition to the market and benefit the public as a whole."

PCGamesInsider.biz has reached out to Valve for comment.