The Legend of Zelda Wii U looks as close to being an open world adventure as the Zelda series has ever come. Though previous games in the series usually featured large overworlds to explore, they weren’t exactly open worlds in the true sense of the term. Consider how Hyrule is physically segmented in The Legend of Zelda: Ocarina of Time. Hyrule Field acted as a vast hub area, with little spokes that branched off to Hyrule Castle, Kakariko Village, Kokiri Forest, Zora's Domain, and Gerudo Valley. Each of these locations was separated from the field with a loading screen, and in most cases, you couldn't travel directly from one to the other without first crossing through the Hyrule Field hub. This didn't feel like a true open world as we think of them today.
The Legend of Zelda: A Link Between Worlds created what felt like a more open world through an unorthodox approach--for the series--to "gating" your progress. Gating is the act of keeping you out of certain areas of the game until you fulfil certain conditions. Again, consider Ocarina of Time: You couldn't enter Dodongo's Cavern without the Power Bracelets. You couldn't get the Power Bracelets until you learned Saria's Song. And you couldn't even climb Death Mountain until you met Princess Zelda and received her letter. A Link Between Worlds did away with this linear progression by allowing you to rent the items you needed to progress in any order, and at any time.
I feel that something approaching this type of gating is necessary for exploration in an open world Zelda game to work. Even if I can travel from one end of Hyrule to the other without a load screen, what is the point if I have to do it in a specific order, anyway? This is a problem that The Legend of Zelda: The Wind Waker suffered from because of the way its vast Great Sea overworld was designed. After a few dungeons, you could sail anywhere, with no loading screens--but there wasn't much reason to until you began the penultimate quest to collect the Triforce pieces. Because it didn't make sense to gate players' movement as they sailed across a vast sea, Nintendo instead placed Wind Waker's gates on the island themselves: impassable obstacles that blocked entry to the island's depths until certain items were acquired. For me, little else defeats the grand sense of adventure than travelling to a new, unknown location, and discovering that I'm not allowed in yet.
A Link Between Worlds gated its locations with items, too--but the difference in that game was that the order you acquired those items was up to you. My problem with that game's item gating was how artificial it felt. Barriers outside dungeons had a picture of the item you needed printed on them--they didn't feel like natural features of the terrain to overcome or circumvent. My hope is that The Legend of Zelda Wii U will find solutions to both of these problems. From what we've seen of the game, Hyrule is a physical landmass, not an ocean. This naturally gives Nintendo far more options for gating progress in ways that don't feel as artificial as an item requirement.
From the gameplay in the video above, originally aired at the 2014 Game Awards, it seems like Nintendo is thinking along similar lines. If I see an interesting landmark in an open world game, I want to be able to travel to it. With Epona galloping through fields, Link para-sailing off cliffs, and setting waypoints far in the distance, The Legend of Zelda Wii U has exactly what I need to spark my initial sense of adventure. However, when I get to that landmark, I want to go inside if it's a cave, or climb it if it's a tower.
This harkens back to the feeling of the first Legend of Zelda game for the NES, and Shigeru Miyamoto's original intentions for it--to capture his feeling of exploring caves in the countryside as a child. This worked for the first Zelda game, because its narrative was not as complex as those of its successors--find the pieces of the Triforce, defeat Ganon, and rescue Princess Zelda. I can accept that The Legend of Zelda Wii U may need to have a main quest line that needs to be followed in a certain order for a deeper and more complex story to work. But if that means I need to explore the open world in a similarly linear fashion, and complete dungeons in a certain order, I'll be disappointed.
How would Nintendo solve that? How would they create a consistent story but still allow non-linear exploration? I have an idea, and it's pretty simple: they could decouple the narrative progression from the item and dungeon progression. Look at The Legend of Zelda: Majora's Mask for an example: the Zora storyline is a self-contained arc which unfolds primarily in the Great Bay. The Gorons' snowy plight is resolved by completing tasks within Snowhead itself. These "story pockets" often required certain items to resolve, and you could bookmark them and return to them if you did discover where that item lay. However, access to those pockets was still restricted by the hub and spoke approach to its world, as in Ocarina of Time. Resolving these narrative events with items is far more satisfying, and feels far less artificial, than opening a new route to travel through, or overcoming a physical barrier to exploration. When exploring an open-world Hyrule, I shouldn't run into those barriers. But if I want to progress the narrative? That's when a hero like Link should run into problems to resolve.