This looks great, do you mind uploading the game to itch.io? I'm weary about dropbox links disappearing :O
Actually, while I have your attention. Can you remove the Dropbox link entirely? Dropbox links don't work in the "External url" field, since it expects to get a URL that is a direct link to the file, not another website where you can download the file. Right now if someone clicks the download button it won't work.