Half-Life 2: Episode Two is the newest installment to the Half-Life series, and was first released in the Orange Box Compilation. It continues Episode One, but the story moves away from City 17 and is instead set in the Wilderness.
Portal is a First-Person Shooter/Puzzle hybrid, where the player has to create portals with a Portal Gun in order to complete the tests of the device.
Team Fortress 2 was the long awaited sequel to Team Fortress Classic. The player plays as either the BLU or the RED Faction, and fight each other with Mercenaries.