Right I finally decided to complete the game on Legendary so I got a friend to go through it on co-op. We finished The Ark but unfortunately the HDD on my xbox died so I lost all my gamesaves.
So my question is, do I need to finish the whole game on a single gamesave to unlock the legendary achievement, or if I do half the levels on one xbox and the others on a new xbox, will I still get the acheivement?