At ConBravo I picked up a Sack Boy from Little Big Planet, and after annoying my fiancee to no end by whistling the theme, I realized how much I thoroughly enjoyed the game, and still enjoy it. It's a simply fun game that focuses entirely on positive emotions. Released in a time when games were obsessing over "moral choices" (would you rather be Satan or Pretty Nice Guy?) this was a game that went all the way back to why we started playing games in the first place, and decided to explore all the good things about the imagination and creativity.
In light of recent "dramatic evolution" in games (cry-wanks like The Last of Us or anything coming from David Cage), it's more important than ever to recognize when a game really gets it right; when a game knows how to make us laugh or smile, even when we're feeling down.
A game that really understands the power of happiness.