very interesting idea! as a Vinesauce fan myself (though I admittedly don't watch all the streamers) I'm definitely looking forward to seeing this completed.

while it seems that all you have done so far is sprite edits and slight dialogue changes, I like what you've got so far. most of the sprite edits are pretty good, I like the addition of the Vineshroom into the moon and the life refill station (though was it in the life capsule? if not, you might want to change that). Vinny and Rev's sprites are pretty good, but I feel like Joel's might need a bit of work. Maybe you could work in the skeleton motif a bit more, since that's pretty much his thing. Though I do feel like the choice of who is in each difficulty mode is pretty good. Do you plan on incorporating the other streamers in some way though? Obviously not as playable characters (although you could add one of them through the mask item), but just through slight cameos. For example, maybe you could replace the guy at the computer with GPM, who is forced to browse Miiverse and begs Vinny/Rev/Joel to save him. Alternatively, whoever is there could've accidentally installed BonziBuddy, though I guess you might wanna save that guy for later. You could just replace the mimigas with each streamer, though that's a bit too basic and stops them from having much relevance I suppose. The use of firin mah lazer is a bit odd though. Like, I know it's a meme, but it doesn't have much to do with vinesauce does it??? i just feel like it's a bit unnecessary and outdated. maybe consider removing that one. the vineshroom farm is neat, but it seems to be missing Jen's, which I feel you might want to add. The edits of the mushrooms to vineshrooms is nice too.

The idea of Grand Dad being the villain I suppose would work, what with him usually being portrayed as evil, but if the mod is mainly aimed at Vinny I feel like you should go with a vinny joke instead of a joel one. Maybe it could be Ralph Bluetawn?

I've never modded Cave Story+ before, so I'm not quite sure how the difficulty settings work, but since each difficulty setting does have slight differences, would it be possible to give them different dialogue? Because if any other crew members make an appearance it'd be a bit weird if they all referred to you as Vinny or *non-specific nickname or pronoun*. Also, if you play as Joel, the babby gun could totally just be named "OMAE WA MOU SHINDEIRU" what with it having the "mark of the Northern Star"

Anyway, I enjoyed this one and despite the slight issues I had with it I feel like you're definitely on the right track with it. The sprite and dialogue edits are all very fun and fitting of Vinesauce. I'll definitely look forward to seeing what else you do with this.