I like it best when a game continues to surprise me. It's something like experiencing a zone with unique graphics and physics, hearing music and convincing voice-acting, and experiencing game physics that are unusual but reasonable, like being able to push enemies off bridges. It's like a wake-up call to walk into a zone that has all of this available and it tells me that the developers of the game really do love their creation and aren't in it just for the money. It's like they are making a promise to their player-base that, no matter what, they will strive to let the game become everything it can be, even if that means taking chances or making drastic changes or sometimes NOT making a change because it doesn't fit the lore of the world.