1. Get rid of heart pieces, jars, and random treasure chests. These items should be obtained from people or objects that would actually have them (You shouldn’t just find Rupees under rocks and by cutting grass).
2. There should be more save slots, three just isn’t enough.
3. Ramp up the difficulty. In particular, the boss battles should help develop abilities for Link, and no two should be designed the same way.
4. Implement a "Trial System" in place of obtaining items as character progression.
5. Puzzles should be based around logical "real world" level obstructions.
6. The story line could use a different direction other than Zelda being captured.
7. Time should not be frozen in towns with more things in game being time sensitive.
8. Items should be context sensitive and have multiple purposes, and combining them should play a larger role.
9. Do away with the Heads-Up Display. Links health would be determined by looking at his state in game, with specific animations to show various injuries and his overall general health. The overhead map could be toggled on and off.
10. There should be story branches allowing for multiple endings, with the option to save the game when finished. You should also be able replay cinematics and set the game to a higher level difficulty.
In particular, I was interested in their “Trial System” and they provided the following details:The "Trial System" would be a method in which Link matures. This includes health upgrades, abilities, and items. Each trial, whether in a cave, dungeon, or overworld, would present a different hurdle for Link to overcome resulting in a new ability or an item to be mastered which would be then available for the duration of the game.