Awesome presentation. I really liked the character sprites with the 3D background. The time effect on the split-screen and player "ghost"was really cool. I also really appreciated the interact symbol, which goes a long way to help players understand what they can do and start actively problem solving.
One downside (that I struggled with as well) is that players don't have anything to do while waiting for their counterpart to do their part of the puzzle. Most notably when the older character gets through the door.