Portal 2 is the sequel of the first game and it has the same principles. You are a test subject (the same as the first game) and you are testing their gadget. A portal gun. A gun that makes holes, like a normal one, but not small ones. Holes that when you get in one, you come out of the other one. You continue the story from were it ended in the first game. Well, kind of. You wake up and you see a little ball talking to you and guiding you. You find GladOS and you wake her up! How stupid of you! You can't really avoid it. Well, after you wake her up you start once again testing. The puzzles are a bit harder that the first game and more interesting. The environment is also bigger and really different than the last game. In the last game, you were in closed rooms with white walls. Now you see plants on the walls and destroyed machinery. You get at a specific part of the game were you are outside. And the graphics are amazing. The game uses the same engine with Half Life 2. It's just amazing. Great experience. GladOS is trolling you even harder now! I love her!