Recently Steam stopped selling the fourth part of the GTA series.
After a short silence, Rockstar Games told Polygon the official reason for the suspension of sales:
Grand Theft Auto IV was originally created for the platform Games For Windows – LIVE. Microsoft stopped supporting the service, so it is no longer possible to generate new keys and continue selling the current version of the game. Now we are actively looking for a way to resume sales of GTA IV for personal computers and share new information after a while.
Recall that GWFL was a necessary component for achieving achievements and playing on the network.
Once Rockstar has solved the technical problems, the game will not only return to Steam, but will surely appear in Rockstar Games Launcher.