7. Portal 2 - The Plot
Valve is known for including hints and clues in lines of code or redundant files in updates, but a lesser known reveal occurs in Chapter 1 of Portal 2. As you try to escape from the Aperture Science facility, you will pass a line of defunct turrets who will shout out to you. One will say "I'm different," in a melancholy voice and if you choose to save it from destruction it will begin to spout seemingly meaningless phrases, however paying attention to these will unveil parts of the plot... The prophecies include "the answer is beneath us," a reference to the hidden underground levels of the facility and will ask you to remember the name "Caroline," which is of course entirely pertinent. After a while it will thank you before you continue with the game having left it behind. This Easter egg is hidden in plain sight and the game rather ingeniously leaves it entirely up to a player's moral compass; whether or not they choose to save the turret or allow its destruction, to give them clues towards the plots narrative thread or whether the player will continue oblivious to its presence. If you have a cruel streak, there's a very good chance you didn't even pause at the poor broken bot.