Many PC owners who got Just Cause 2 via the Steam service are not able to download or play the game, as the title no longer appears in their libraries. Valve is apparently looking into the issue.
Update: The issue seems to be resolved. If Just Cause 2 hasn't reappeared in your library, restart the Steam client.
Just Cause 2 came out many years ago, and on the PC it was distributed digitally using Valve's Steam service.
Thanks to many sales and the recent release of the Just Cause 2 Multiplayer mod, quite a lot of Steam users own the actual game.
Now, however, due to an error, it seems that Just Cause 2 no longer appears in their game libraries. As a result, owners can't download or play the game.
According to the SteamDB Twitter, Valve is looking into the issue as apparently there has been a pretty major error.