Blade, I have NOT read you GDD but I do have a question:

You do realize that fan games are illegal?
Even if you release it for free, it is illegal to use another persons copyright without their permission. As I'm going to assume you do NOT have WB or JKR's permission to use the HP IP, then I suggest you start designing your own game instead of basing it off of something you will never be able to make.

It is easy to create a world with wizards and monsters and it doesn't have the HP label on it.

Just an FYI before you spend too much time designing a game that is illegal.