Steam page of Grand Theft Auto 4 no longer allows players to purchase the game, although there’s no explanation as to why. GTA Vice City briefly disappeared in 2012 due to a copyright claim regarding Michael Jackson’s Wanna Be Startin’ Something, but Rockstar have been more careful with copyright issues since then. For example, in 2018, GTA 4 was updated to replace some songs from Vladivostok FM before their copyright expired.
Another possibility related to Games For Windows Live. Every game on GFWL need a specific key from Microsoft, and Valve may have suddenly run out of key or have problems extending service. With luck, perhaps Rockstar will be able to remove GFWL from GTA 4.
It’s also possible that Rockstar will pull GTA 4 from Steam completely before making the game an exclusive to Rockstar Launcher. Those who purchased GTA 4 on Steam will still keep a copy of the game and can download it in the future.
Source link: GTA 4 was suddenly deleted from Steam
– Emergenceingames.com