Valve has introduced the ability for developers and publishers to offer downloadable content through Steam, just as Microsoft and Sony do with their console platforms.
This means that any game attached to Steam - whether it was bought direct, at retail or elsewhere online - can now use Valve's platform as a one-stop shop for add-ons.
It also means that publishers are now in a position to charge for downloadable content through Steam. The first example of this is The Maw, from Twisted Pixel, for which two new levels are available for GBP 1.10.
"We're happy that we can now offer Steam customers significant expansions to the Maw story," said Twisted Pixel CEO, Michael Wilford, adding: "delivering more Maw directly to gamers while they're still playing the game."
Valve has a well-known aversion to premium DLC, arguing that if consumers buy the game they should get all the subsequent content as part of that outlay.
However, the company's publishing platform is a discrete but connected entity, and doesn't tend to discriminate against clients with other ideas about how to do things.