what are you rewarded with?

also what you said seems a lot like skyrim but without the tons of side missions, is there any difference between the exploration with skyrim and Xenoblade?

exploration like metroid prime.. I mean like little puzzles trying to find new pathways and a bit of backtracking..that pretty much defines exploration for me :*D

I have a feeling that the Witcher 3 will offer some of the greatest exploration in an open world ever. Call it a hunch

Something like GTA vice city are a bigger version of sleeping dogs.

I liked final fantasy XII, I spent 5 hours exploring the desert the first time they open the doors.

^this

Actually there are tonnes of side missions in Xeno, I think like 50-100 in the first zone alone. The game rewards you in a bunch of ways, some traditional, some unique. Exp and skill bonuses, are some, as well as finding unique items, quests or places where you can find needed items easier. But it also rewards the player with unique glimpses into the world around you. For example, the game world you are exploring is a giant titan. You are walking through forests and planes and ruins that are built on top of the giant creature's legs, arms, wings, etc. Throughout the game if you walk off the beaten path you may get a glimpse of the creature's leg descending down to the endless ocean, or a creepy view of the rival titan staring you down with evil red eyes from hundreds of miles away. It ads to the atmosphere and mythology of the world and is verymuch like real world exploration and the intrinsic rewards you get from exploring a new place. Also, since almost everything you can see is reachable, it's like the whole world is teasing you or challenging you to try to find a way to reach every point. When you do you may find an ancient ruin or new side story to play out. Also, you get a bonus when you discover everything on a map.

I agree Super Matroid and Metroid Prime (the first) are good examples of exploration. It's difficult to explain why if you haven't played them. Let's say the exploration is "good" when gameplay and structure of the game rewards you if you observe the eviroment carefully and you interact with it.

In Metroid in particular exploration is non-linear:, since you gain new abilities gradually during the game, you have to return  in places you have already visited to open up new paths and to find hidden items.

Something like the first Jak and Daxter. or GTA: San Andreas.

I would simply like games that should be more open / explorative to actually be more open and explorative going forward. The two games that come to mind here for me are the recent 3D Mario titles, as well as the Fable series.

The recent Mario titles especially Galaxy, while boasting great gameplay and design, have been far to linear for me. I miss freely exploring huge, continuous worlds in my 3D platformers a la Banjo Kazooie, being able to seek out hidden areas and objectives in almost any order you want as opposed to the linear structure of the Galaxy games.

The Fable series I have a similar complaint in that these games are broken up into smaller regions that aren't seemelessly connected, and beyond the main paths and a few key waypoints, there isn't really much to explore. Just simply go to the next main quest or side quest points of interest n thats it.