First thing to take a look at, considering it's a large portion of the game, is the menu system. Here is a quick idea of how the menu system will work itself out.
Large Version
Now what you're seeing here is the basic idea of the menu. The numbers 1 through 5 are individual menu items which make up the entire menu. Each of the Menu Items will contain actions that will be called upon by keypresses. As of now, I'm thinking just the actual keyboard numbers 1 through w/e number will be used for the keys, but that may change later on depending on how the gameplay goes. Everything else should be clear from the picture.