The Windows PC versions of Ubisoft's Assassin's Creed Unity, The Crew and Far Cry 4 are no longer being sold through Valve's Steam distribution service. Other Ubisoft-published titles that have already been released, however, remain on the store.

PCGamesN reported earlier today that the trio of upcoming Ubisoft games had been pulled from Steam in the U.K., but the removal of the PC versions from Steam now appears to be global. Ubisoft told PCGamesN that it was "in discussions with Valve about Assassin's Creed Unity" on Steam's store, but offered no clear explanation for why the title had been pulled. The new Assassin's Creed is scheduled to launch next week.

Assassin's Creed Unity, The Crew and Far Cry 4 are available to purchase on other PC game digital distribution sites, like Ubisoft's own Uplay, Green Man Gaming, Amazon and GameStop.

Polygon has contacted Ubisoft and Valve for comment, but neither company has responded with a statement.

This isn't the first time Ubisoft-published titles have been missing from Steam. In 2012, the PC versions of Assassin's Creed 3 and Far Cry 3 were slow in coming to Steam in the U.K., despite being available in other regions. Valve and Electronic Arts clashed over how in-game downloadable content was sold the year prior, which led to Crysis 2 being removed from Steam for a while.