There are a lot of games that I love very, VERY much, but I can't think of one that I'd call perfect. Maybe the original arcade Donkey Kong? The original Pac-Man and Ms. Pac-Man maybe? The more complex a game is, the more likely there'll be little, minor things that kind of put me off. But the trade-off is that the more complex a game is, the more likely it can provide a deep, immersive experience. Those minor issues are nitpicks to be sure, but they still keep the game from "perfection."