Exploration in games is a great motivator

I love games with a good sense of exploration. The Legend of Zelda: Wind Waker, Castlevania: Symphony of the Night, Fallout 3, and plenty of other games stay in my memory of how because of how great the exploration is. Being able to go where you want, and always being able to find something new is one of the most fun things that you can have in a game. In Wind Waker, you can sail around the world, and each section of the map contains a new place to explore. In Castlevania, you can travel around the map to find new abilities and power ups for your character, and each area you enter has memorable scenery, music, and enemies. In Fallout 3, no matter where you go, there is a good chance that you are going to find a new quest, a new building, or a new character to interact with. I feel that the element of exploration is important to just about any game, because you are being rewarded for seeing more of what the game has to offer; and if a game doesn't feel rewarding to play, is it really very fun?