First of all, this is no game but a virtual interactive book, and a very good one as a matter of fact.
To everyone who is interested in the behind the scenes of Portal 2, and how a development of a game works at Valve, you're in for one hell of a ride. I absolutely recommend it, it shows the everyday routine of an employee at Valve, some very enlightening points of view on their known delays and some videos plus slideshows to keep you interested while reading. If you read it all calmly and with some attention it will take you a bit less than an hour to go through it all, but I assure you, it's absolutely worth it.

The Final Hours is not a game (though can't you imagine one - set perhaps during the Seven Hour War, trying to escape as the facility collapses and the Combine invade the test chambers?), it's a book. It covers how Portal was created, the complex gestation of the sequel, and the personalities involved at every step.
The book is interesting, revealing a lot of behind the scenes info. You learn what a complicated business creating a computer game is, especially a Valve one, and something of the stresses involved. For even at a company like Valve, creating a game is hard work, and it takes its toll. The book makes what use of its computer nature as it can, embedding videos and interactive content. They do not add that much overall though - the pictures and words are what matter.

While some of the background about the development of Portal 2 is very interresting to read, I can not recommend to pay for this "App" because its broken and not cared about for some time. And so many links in this document, that might have brought some extra depth at release in 2011, simply don't exist anymore and you get pages full of error code.
Meh =/

I gladly pay some € for an insight article about Valve, but this presentation has aged badly and is just super outdated in 2021, sorry Geoff.

Portal 2 - The Final Hours is a book, not a game. However, that doesn't mean it's not worth looking into! This only really has value if you've played Portal 2, and especially if you liked it...and especially if you're interested in how it was made/behind-the-scenes info, and ESPECIALLY if you're into game game-making process in general. It has a lot of neat little tidbits to learn that really makes you appreciate Portal 2, an already stellar game just to play, even more.
It's not walls of text, but instead has plenty of pictures and little sidenotes. And, of course, little interactive bits where you can click on things or slide the mouse. But really you're getting this to read. This isn't a long "book;" I finished it in a few hours in one sitting. Though that's probably a good thing, as it still had a lot to read about and kept me engaged the whole time.
This is more or less a guaranteed recommendation if it looks interesting at all to you. I'd probably wait for a sale even at its low price if you're fine with waiting, but $2 for some neat knowledge is a fair trade to me!

Many functions do not work anymore, like panorama pictures. The resolution of the texts is quite low, not aged well at all.

Don't buy until they fix this. Until then, a PDF file is even better.

IT'S NOT A GAME! But it's a very interesting reading if you are interested in the creative process behind Portal and how everything in Valve works. Some things i already knew, but i learned many after reading it. The interactive features also turns it more easy to read. I'll recommend it only if you are a Portal/Valve fan and you want to know more about how it was made, but it worth the low price it has. (if you are a fan, BUY IT NOW)

would not work because it uses adobe air. Would recommenced if it did work.

Get this if you are a geek about how games are made!

text is pretty unreadable and many elements don't work anymore. don't buy this until it gets a patch

Book.