Activision has removed Teenage Mutant Ninja Turtles: Mutants in Manhattan, TMNT: Out of the Shadows, The Amazing Spider-Man and its sequel from Steam, PlayStation Network and Xbox Live.
The reason for removing the four titles from digital storefronts appears to emerge from Activision allowing the licensing agreements to expire. Spider-man is especially key as Insomniac is currently working on a PlayStation 4 exclusive entry in the superhero franchise.
The removal of Platinum Games’ Teenage Mutant Ninja Turtles: Mutants in Manhattan seems less understandable as the game, which was mediocre at best, is only 8 months old.
For people who already own the games, you can continue playing. However, you cannot buy the games going forward from the digital store, you can still pick them up on disc, at least for the foreseeable future.