I have seen games with similar styles out in the mainstream, but this one is very unique in the sence that it is in a school setting, so I think I will keep up with development. And as for unoriginal content, if you do choose to use other peoples work, I recommend making sure it isn't very commonly used and you give credit to the creator. In the case of Minecraft, they have many sound files from a rather obscure website, and they do (or used to?) mention that website in the credits.