6. Portal 2 (PC/Xbox 360 – 2011)
This game is peak Valve! Super intelligent game design, with intriguing puzzles, fantastic production values, a great story with hilarious characters and voice acting. The pacing of this game is really spot on. I like Portal 1, but it kind of felt like a demo, Portal 2 is a much bigger game, and a masterpiece at that. I have no complaints really. People are asking for a Portal 3, which I am sure would be cool, but I do not think it is needed, Portal 2 is already perfect and comes to a satisfying conclusion. It is not like Half-Life that left us on a cliffhanger, which is still waiting to be resolved 14 years later.