This hack just got updated again as recently as yesterday so I think it should be fine for me to post in this thread even though it hasn't gotten a reply in so long, even if necroing threads is normally a concern (I'm not sure how it gets treated in this community).
I just wanted to give some feedback and say that I really appreciate that you are still updating this hack, as well as that you made it in the first place. I played it in the past, though I didn't really get very far but hopefully that will change soon.
Sandbox Mode in particular is interesting to me because it opens up so many new possibilities for the player! Sure, you can use it for game-breaking things if you want, but it is not at all limited to just that. For example, maybe after you played Puppet Dance Performance, you wanted to try starting with whatever puppet you felt like starting with in Purple, instead of being limited to only the puppets that are available early on.
If I make a rom hack of my own, I probably will draw inspiration from Sandbox Mode in order to give more options to the player, and as a result, hopefully greatly enrich their experience.
Again, thanks so much!