Overall sounds like a fun idea, however the game treatment section needed to unpack some of the aspects a bit more like what kind of spells would be available, what constitutes "fighting", etc.
As such, it is difficult to understand the scope of the game to be implemented, and hard for me to provide much guidance on this. My advice is to get down on to paper the list of features you would like to implement and prioritise them. I'm happy to assist talking about this