https://wccftech.com/gta-iv-steam-gone-games-for-windows-live/

Grand Theft Auto IV may be one of the biggest games of all time, but if you want to buy a new copy on Steam, you’re currently out of luck. Over the weekend, GTA IV disappeared from Steam without explanation -- those who already owned the game could still play it, but new purchases weren’t allowed. Of course, a game as significant as GTA IV doesn’t just disappear -- clearly something strange was going on. Now we know what that something is.

As some speculated, GTA IV’s reliance on the outdated Games for Windows Live platform is the culprit. For those who don’t recall, GFWL was essentially a PC version of Xbox Live, which was discontinued when Microsoft brought the actual Xbox Live to PC. GFWL games require keys generated by Microsoft, and it seems as though Rockstar just ran out of keys. Here’s what they told The Verge about the situation…