The European Commission has announced plans to investigate Valve and five PC game publishers over suspected anti-competitive practices.

The investigation revolves around the use of activation keys.

The Commission wants to work out whether the companies are in breach of EU antitrust rules by preventing consumers from enjoying cross-border choice.

The suspicion is that agreements between Valve and the publishers break EU competition rules by unfairly restricting retail prices or by excluding customers from certain offers because of their nationality or location.

Digging into the detail of the investigation, the Commission is looking at bilateral agreements between Valve and five publishers: Bandai Namco, Capcom, Focus Home, Koch Media and Zenimax.

The investigation concerns geo-blocking practices, where companies prevent consumers from using digital content, in this case PC video games, because of the consumer's location or country of residence.

The Commission wants to find out whether the agreements between Valve and the publishers require the use of activation keys for the purpose of geo-blocking.

Say, for example, you receive an error message from Steam when trying to activate a game with a region ID different to that of your local account. According to the European Commission, that's in breach of its antitrust rules.

Here's the EU Commission:

In particular, an "activation key" can grant access to a purchased game only to consumers in a particular EU Member State (for example the Czech Republic or Poland). This may amount to a breach of EU competition rules by reducing cross-border competition as a result of restricting so-called "parallel trade" within the Single Market and preventing consumers from buying cheaper games that may be available in other Member States.

The Commission has just opened formal proceedings, and it noted there's no legal deadline for bringing the investigation to an end, so it could go on for quite a while, depending on the complexity of the case and the cooperation of the companies involved.

If it rules Valve and the publishers are in breach of its rules, the EU Commission could open the door to gamers legally buying games in another EU country's online store at potentially cheaper prices.

In terms of its impact on UK users of Steam, in a pre-Brexit world we fall under the EU antitrust rules, but in a post-Brexit world, we may not benefit from the Commission's ruling, whatever it may be.