The trinity-based puzzle game Trine came out of nowhere when it released in 2009, the heyday of unexpected indie games. Its sequel, Trine 2 , takes everything from the original and smooths it, refines it, and makes it better. With the addition of online co-op, you can pass control of the other two characters over to friends. Instead of switching back and forth to play all three perspectives yourself, there's something so much more gratifying about levitating a box to literally give a friend a hand-up. The colorful environments and soft, almost relaxing puzzles are just a bonus.