Vidmaster Challenge: Deja Vu is probably my favourite achievement in the history of Halo.
The player, along with three friends, have to complete Coastal Highway on 4-player Legendary Live co-op, with the Iron skull on, and without using the 'Hog or Scorpion.
Anyone who has done the Vidmaster Challenge: Annual knows how painful that one was, and also knows that four Ghosts will spawn once you kill 343 Guilty Spark and leave the building, which is the only way to complete the level with the achievement.
In ODST, with the Iron skull on Legendary, the game spawns four 1,000 shot Rocket Launchers, along with a Mongoose for each player in the first tunnel on the highway. The Rocket Launchers are separate weapons to the normal 8 shot Rocket Launchers, allowing the player to have two Rocket Launchers on his person at once.
What makes this my favourite achievement is the fact that it's so satisfying to be in a squad of four other Rocket Launcher toting people running down a highway destroying everything in your path.
At the end, you'll come to a building that you have to defend. This wouldn't be so hard if everyone didn't have Rocket Launchers. >:^D
We only died at that part because we got bored when we hit checkpoints and started firing at each other.
I absolutely loved the ending to Halo 3 and the same goes for the ending to ODST. If Bungie can do something more fun than that at the end of Reach, I will eat one of my computer speakers.
