It's down to only 20 bucks now.... 5 games for 20 bucks, what are you waiting for?!
Now... reviewing game for game i could not start with any other than Half Life, since it's the one that ties together the package. The game developed a great story. I spent more than 20 hrs on it so its great gametime for a FPS. What makes the gameplay great is that you are in control of your surroundings, after achieving the gravity gun the killing combinations are endless. I've spent some time just launching soda cans to those pesty soldiers, it's a lot of fun.
Portal, despite the shortness of the game you'll enjoy every minute of it. It's nothing like you have ever played and with Portal 2 getting closer it's a great time to check it out. It's the cherry on top of the cake, but you know what they say about cake...
Team fortress 2, a very comical and clever online multiplayer. I don't know what to say about it cause by now the Orange Box already had me dazed by its magnificence. How do you top the untoppable? With Team Fortress 2.
Enjoy the game, because you will get it... eventually, there's no escaping it. :)