Portal 2 ($9.99)Image by ValvePortal 2 may be the perfect game. It’s a puzzler at heart, but it injects those puzzles—which involve the best placement of the titular portals, which you create with a gun—into a masterful concoction of science fiction, memorable characters, and even a catchy song. It’s both memorable and challenging, and those challenges are designed in such a way that you feel triumphant when you finish.To read this article in full, please click here