Fair enough criticism here, but this is a high schooler. Instead of coming on strong with HEY WHERE IS THIS AND THAT, understand that he "open-sourced" the project to learn stuff. So since I don't have the proper knowledge to explain the open-source license stuff, maybe you could explain a bit or point to a good read so he/she can continue to learn.
Cool project! Anyone trying to run it on *nix will need to open Main.java and replace all instances of the windows-specific file separator "\\" with "/".
Where is your LICENSE file? Where are licensing terms discussed?
Open source isn't just code; the license you release under is equally, and perhaps even more, important than the code.