The Orange Box is a great game.

First off, Half life 2 (and episodes 1 and 2). This game has a fairly nice story, and is very addictive. The combat is great (partly thanks to the gravity gun, a weapon that lets you hurl most any relatively small object in the game at your enemies.) and the boss fights are amazing. The game also tends to differ in the "horror rating" depending on the stage. While some stages are pure sci-fi action, others are quite scary. On the stage called Ravenholm, it startes you off in the middle of the night , facing a tree that has the bottom half of a body hanging from it by a rope.you later find the top half of this body on table in a shed with a giant razor in its back.
Second in the box, Portal. This Game is amazing. You are a test subject in a facility run by a quite humorous cake-obsessed computer. You are given a tool called the portal gun, which you can use to get over high places by shooting a portal on the ceiling other side of the high place, and then one under your feet. You can make very long jumps using momentum, and make turrets fall from the ceiling in another room. You use this gun to complete various challenging puzzles, and to try to escape the reseach facility. Also, when you beat the game, you are rewarded by the very funny song, "still alive".
And last of all, Team Fortress 2. This game has simple, but nice graphics, no story whatsoever, but is very, very fun. There are a variety of classes, and each is completely unique. There is the pyro, who wears a gas mask and is equipped with a flamethrower, The scout, who is very fast, equipped with a sawed-off shotgun, a baseball bat, runs fast and can jump again in mid air, the spy, who can turn invisible, or wear a disguise that makes him look like the other team, and is equipped with a pistol, a knife, and a "sapper" which destroys creations made by and engineer, and many more. The only problems i have with this game is that if you are not hooked up to the internet on your PS3 or 360, you cannot play it, and when you are it has quite a few bugs.