The Timeshift Stones and Timeshift Orbs are both wonderful ideas implemented beautifully into Skyward Sword. The way you could interact with people from the past, as well as use the stones and orbs to activate/deactivate things made for great puzzles and great gameplay in general. A whole game based around it though? That sounds really great actually... I would be one to make a flash or Game Maker game based on this idea. If it didn't get repetitive, as in, it had a variety of puzzles based around it but they weren't the same thing over and over... this would be a great idea!
:yes: