It's sort of like buying five Halo-quality games...for around $8-10 apiece. You can't argue with a deal like that.
The thing about the Orange Box is that it is simply the biggest deal you could EVER make in the history of gaming. There are five hilarious, Halo-quality games on one single disc. Between Half-Life 2, Episode One, Episode Two, Portal, and Team Fortress 2, you will find yourself in over 25 hours of the most enjoyable gameplay experience you've had in your whole life.
Let's start with The Half-Life series, shall we? The Half-Life 2 component of the game will take up three-fifths of the whole game, but it is easily over 20 hours of entertainment ALONE. Half-Life 2, Half Life 2: Episode One, and Half-Life 2: Episode Two are graphically impressive, and the storyline is simply immersive. In the game, you are plunged into the first-person view of Gordon Freeman, an incredibly skilled scientist who rebels against the Combine, an alien force that is in control of the world's laws and freedoms. You, along with other human inhabitants, are slaves to this powerful alien force. You eventually meet up with some familiar faces from the first Half-Life game (which you don't need to play to understand the plotline in this game), who help fight back against the Combine. As hours of gameplay go on, more and more plot points are unravelled, leaving you always hanging as you move from one chapter to the next.
Portal, the fourth game on the Orange Box, is the funniest game I have ever played. Ever. Even that feels like an understatement. You play as Chell (as stated in the credits) and awaken in a testing chamber to the sound of a robotic voice over an intercom. This robotic voice is the voice of GLaDOS, an AI voice that helps you with the complex tests ahead of you, and makes the most hilarious sarcastic kinds of jokes you could ever hear.. In each test chamber, there are two portals: a blue one and an orange one. This works so that when you enter a blue portal, you come out the orange one, and vice versa. Eventually, you gain the ability to shoot portals yourself, leading to far more mindbending tests. As you move through the test chambers however, you soon realize that something far more sinister lies beyond the innocent-looking test chamber. Portal alone makes this game worth a buy.
Finally, there's Team Fortress 2, the online component of the Orange Box. This component of the game is another great addition, with a cartoony kind of feel added to an FPS game. There are a certain amount of classes to choose from, and a wide variety of skills come with them. The only problem with TF2 is that there are very few maps to choose from, but even this doesn't hinder the gameplay experience one bit.
The Orange Box is the greatest video game deal out there, hands-down. The amount of value in the game is immesurable. The single player component alone will take up to and beyond 25 hours, while Team Fortress 2 also provides countless additional hours of fun to that.
No matter who you are, even if you never were a fan of Sci-Fi FPS games, this game is worth more of a buy than any other.