Valve have a great, mischievous sense of humour. Their games are often full of little secrets, surprises and other easter eggs for players to find. Of course, they're not always in the most obvious of places. Enter: The PC Gamer Portal 2 Secrets Guide. We've scoured Aperture Laboratories in search of all the cool little extras Valve have hidden away, and put them in this handy little guide to help you discover them for yourselves. Look, there are even fancy videos to show you how to get to the trickier ones! Some of these secrets are quite far into the game, and in order to show you where they are, we have had to include a few minor spoilers, so be warned!
The Final Transmission
Known as 'Rat Holes' in the community, these are little areas behind the bright white walls of the test chambers. You'll easily recall the ones from Portal, which were full of wall scribblings declaring that 'The Cake is a Lie', but there's plenty more drawings to find in Portal 2. The first rat hole can be found during Chapter 2 in the Advanced Aerial Faith Plate chamber. It's located up in the corner by the tilted wall panels, and by placing a portal in the right hand panel and a second in the wall to the left, you can be flung through into the secret room. You can also grab an achievement here - Final Transmission - by taking a radio into the rat hole with you. Follow the video to see how!
Turrets are odd things. They're remarkably cute for a little android, but they are also full to the brim of big, nasty bullets. More often than not, those bullets have got the name 'Chell' stamped all over them. However, there are a few turrets that aren't out to reduce you to a holey mess. To find these tuneful chaps, you'll need to drop down into a secret area below Test Chamber 16, which you'll find during Chapter 3. Follow the video, find the 'bots, and have yourself a little dance. There's also a bit of art in there too, depicting something less uplifting...
Another rat hole can be found in Chapter 3 in Test Chamber 17. It's located up near the top of the room in a ventilation shaft, so you'll have to make use of the light bridge in the room to get there. Watch the video, then take a trip there yourself.
No Hard Feelings
To get the No Hard Feelings achievement, you're going to have to save a special turret from destruction. You'll find him on the disposal line in the factory during your time there in Chapter 5, not that long after you've escaped from GLaDOS. On the second conveyor belt, look out for the laser sight and a turret shouting "Help! I'm different!" Pick it up to gain the achievement.
Potato Powered Flux Capacitor
Who'd have thought that a mere spud could generate 1.21 gigawatts of power? The daughter of an Aperture employee, apparently. Whilst Wheatley is helping you through the dark areas of Chapter 5, you'll come across the Bring Your Daughter to Work exhibition, where you'll find this little Back to the Future reference.
Also found at the Bring Your Daughter to Work exhibition is this horrific monster of a potato, which appears to be growing into the ceiling. Strange as the potato may be, even stranger is the person responsible for this monstrosity. The project is signed by 'Chell'. Does this mean Portal 2's protagonist is the daughter of an Aperture employee? Could she even be the child of Cave Johnson himself? Get your conspiracy on!
To gain the Door Prize achievement, you're going to have to use the intercoms on the five Vitrified doors located around the original Aperture Science labs. They are pretty obvious when found, but they are hidden in some less-than-obvious places. The first two can be found fairly easily, right after you finish the long elevator ride after the first set of Repulsion Gel test chambers. The final three are in the Control Room, which can't be missed. Follow the video to find the hidden door for the corridor containing the final three doors. Remember to hit the intercom on all five doors; otherwise you will not get the achievement.
The Ship Overboard achievement is a great little nod to Valve other masterpiece; Half-Life 2. Players of Half-Life 2 may recall Dr. Kleiner talking about the Borealis near the end of Episode 2. That ship was an experiment of Aperture Science, and here you can see the dock from which that very ship launched. You'll find the dock behind the door in the control room (see the Door Prize video for how to find the control room). Follow the corridor to the end and you'll find the dock, complete with Borealis life preservers. Look directly at the life preserver to gain the achievement.
Portrait of a Lady
During Chapter 7 you'll do plenty of experimenting with Propulsion Gel. After the test chamber with the ramp puzzle, there is an opportunity to access a secret room to see a portrait of Aperture CEO Cave Johnson with a mysterious woman, who GLaDOS finds 'familiar'. Viewing the portrait also bags you the Portrait of a Lady achievement.
The picture has more to reveal than just an achievement though. The edge of the painting is very dark, but by the power of modern science (or just Photoshop) you can see than when the image is brightened, to the left of Cave is a young girl standing by the book shelf. Who is this girl? And how is she related to Cave and the mystery woman? The plot thickens!
After Wheatley's gone a little... mad, he'll start setting up new test chambers for you to conquer. During Chapter 8, when you first enter Chamber 15, Wheatley will break a few walls bringing the 'exit' part of a test chamber in to your area. As the walls crash down, you'll be able to catch a glimpse of P-Body – one of the robots from the co-op campaign – making a hasty getaway.
So that's the collection of secrets and easter eggs we've found so far. But, knowing Valve, these finds are probably just the first of many. Have you found any other secrets? Let us know your discoveries in the comments!