To save you having to go through the entirety of the game from the beginning, you can save your game just before the end.
At the university, and having followed the red wire through the tunnels, you'll reach the final metal door. Open it, but before entering, save your game. Enter the door and the final cut scene and credits will roll. When you get to the Main Menu, reload your save and enter the metal door again. Once the credits have rolled, you'll be rewarded with the achievement.