A UK tribunal has given the go-ahead to a £656 million ($901 million) collective action lawsuit targeting Valve over alleged anti-competitive practices on PC storefront Steam.

The legal action, originally filed in 2024 by digital rights campaigner Vicki Shotbolt, has now been given the green light to proceed following a ruling by the UK's Competition Appeal Tribunal, BBC News has reported.

In short, Valve is accused of wielding its status as the dominant digital game storefront to lock game developers and publishers into release parity restrictions, and keep game owners spending on Steam when buying add-ons.

Shotbolt's lawsuit is a collective action claim, effectively a class-action suit, which she is attempting to take forward on behalf of the 14 million UK citizens who have bought games or add-on content through Steam since 2018.

The tribunal's new ruling, published this week, takes into account Shotbolt's claims and an initial response by Valve designed to halt the legal action from progressing further.

The lawsuit alleges that Steam unfairly imposes platform parity obligations which prohibit publishers from selling games on rival stores with better terms, causing a restriction of competition. The legal action has also taken aim at the need to continue buying add-ons for games bought through Steam via Valve's own marketplace, leading to a further reduction in competition. Finally, it alleges that Valve imposes unnecessarily high commission charges — essentially, the typical 30% cut it takes when you spend money on Steam — which results in higher prices for consumers.