We mentioned yesterday that Ubisoft had removed Far Cry 4 and Assassin's Creed from the UK steam store. Reports are suggesting that this is happening on the US version of the store as well.
There is still no explanation as to why this has happened but it looks like both of these games have turned up on Origin now instead. There are also reports that The Crew is on there but as of now it is nowhere to be seen.
Hopefully we get an explanation as to what is going on soon as I don't think anyone wants to be buying these games from either the Origin or Uplay services.