Steam is facing a £656 million collective action claim, brought forward by a digital rights campaigner who has accused Valve of using market dominance to overcharge 14 million UK consumers.
The claim was filed at the Competition Appeal Tribunal on June 5, brought forward by Vicki Shotbolt.
"Valve is rigging the market and taking advantage of UK gamers," Shotbolt told BBC News.
She said the claim was filed "to stop this unlawful conduct and have people get back what they are owed."
The claim also accused Valve of "forcing" publishers to sign up to pricing restrictions, in addition to charging publishers commissions of up to 30%.
"We believe that Valve has been unfairly shutting out competition for PC games and in-game content, which has meant that UK customers have paid too much for these products," a statement read on an accompanying website for the claim.
Shotbolt is represented by Milberg London LLP, which represented consumer rights expert Alex Neill in bringing forth a similar claim against Sony in 2022, in which the firm was accused of overcharging players, developers, and publishers.
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