Tomb Raider multiplayer developed by Eidos Montreal
Why do single-player games need a multiplayer side bolted on? Because you, buying public, are reluctant to buy and keep them if they don't. This can interfere awfully with development, but thankfully many games hand this off to another studio so the main game doesn't suffer. Square Enix has confirmed that's what's going on with the shiny new Tomb Raider's recently-confirmed multiplayer side, which is good news.