Spider-Man: Web of Shadows: Spider-Carnage is an unlockable alternate costume for Symbiote Spider-Man.
The DLC for him and the other characters was later brought back in 2016 for the game's PS4 and Xbox One-exclusive rerelease. Ultimate Carnage was unlockable as an alternate costume.
Since then, Carnage has become one of Spider-Man's most (in)famous villains, appearing infrequently in the comics before seemingly being killed off after Mac Gargan became a more monstrous version of Venom.