Developer Wolfire Games filed an antitrust class-action lawsuit against Valve claiming that Steam has usurped around 75 percent of all PC games spending.

“Valve’s scheme imposes a massive tax on the PC Desktop Gaming industry,” the complaint reads. More specifically, the developer suggests that Valve is getting “over $6 billion” in revenue each year from Steam’s 30% cut.

According to Wolfire, Valve abuses its market position by contractrually forcing developers and publishers to offer the best price on Steam, making it difficult for other platforms to compete.

In addition to hurting competitors, Valve’s policy is detrimental to developers and gamers, the lawsuit claims. “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.”

That’s not the first antitrust lawsuit brought against Valve this year. In January, a similar lawsuit claimed that Steam Distribution Agreement is “anticompetitive and constitutes illegal monopolization and monopoly maintenance.”

Valve is yet to respond to this.