Wow, you're quick. Literally just joined lol. Actually made an account to download the Cave Story Geobox Engine, until I realized the creator never gave out download links. A forum post from 2017 said that some people have the link? Though I don't know who to ask for it, and I don't want to accidentally break any rules considering I just joined. So for now, I'm using Quote99's WebGL engine which is pretty similar.