In order to celebrate the successful launch of the Perpetual Testing Initiative for Portal 2, Valve has launched a Weekend Workshop Sale on Steam, allowing gamers to pick up Portal 2 for 66 percent off and to get The Elder Scrolls V: Skyrim with a price cut of 33%.
There are also half-price items available for Team Fortress 2.
Since it was launched on Tuesday as free downloadable content, the Perpetual Testing Initiative editor has been used to create more than 35,000 new levels for Portal 2 and these have been downloaded by the fan base more than 1.3 million times.
Skyrim is included in the Workshop-themed sales because Bethesda has made it easy to deliver mods to players via Steam, resulting in more than 13 million of them downloaded by players.
Portal 2 was one of the most successful titles of 2011 and Valve has already said that it might deliver more content for it even as the community builds its own content.