I'm really really sorry this only has two ratings! This is an incredibly well polished, creative game that clearly had a lot of work put into it and needs more attention!!
First of all, lots of great stuff here. I love the way you can switch between the characters and have different abilities. Using the butterfly net to grapple is so creative, and grappling is a mechanic I've never seen in a platformer before! Very clever! The level design is also great... very open feeling with lots of great platforming. Character animations, backgrounds and music are all fantastic, and I love the art style of the dialog box characters!
The only thing that stuck out to me a bit was the writing. You've definitely nailed the character dynamic between Jay and Chichi, and you've got their personalities down pat. But I feel like you could do way more with that in giving the dialog voice. There were a lot of lines that sounded a bit too generic, like textbook adventure game stuff. This not only took away from the charm of the characters, but also kinda made the games incentive a little less exciting. Now I do get that part of the reason for the generic dialog is that Jay is trying to keep the objective a secret. But even then, it's important to find specific ways to be vague.
I think the first step to tackling this generic tone would be to take your game's script and copy and paste it into a Word Document. Then use the "find" feature to see all of the times you used the word "adventure" ... and also the word "treasure." It's quite a bit, I'm afraid. Take a look at all those instances, and think about them in the context of your characters. How can they make it more specific? Whether it's a little inside joke, a specific reference to a previous adventure, or just word choice that shows their opinion more clearly, all of these things would help add voice to the script.
Just as an example, there's one part where Jay is talking about how the treasure they will find will be better than a pinecone, then Chichi says something along the lines of "*sigh* this better be a good treasure" ...
consider something more like "*sigh* This better not be some pointless trinket... again..."
or if you want to get even more specific
"after the frog fiasco, I'm not sure I trust your judgment on what constitutes as valuable."
Kinda like that! immediately adds a lot more voice. You've already got two wonderful characters, so all you gotta do is dive into their mindsets and find the perfect words to really make them come to life ;)
I hope these suggestions are helpful to you! Congratulations again on finishing a great game!
-Sasha