This is a pretty cute experience I just spent my morning going through. I do like the concept of being able to take actions that alter the world in such a way that other actions become unavailable. It's possible to obtain multiple certain treasures before having to use the time box, which goes against the theme of the game, but this was still a treat to go through. Your brother did some nice work here!
Curse of the Nine Treasures
There's a small island, twenty days north and thirty days east of Parter Town, in the heart of the ocean itself. An island inhabited by monstrous creatures. Buried within are nine unique treasures, however, there is a catch: Due to a millennia-old curse, if one were to take one of these treasures, it would permanently lock away all the rest.
Not that some silly old curse is going to stop Captain Hookbeard.
Collect items, solve problems, and talk to some... Unique individuals, to collect one of the nine treasures, then reset time to try something different!