Wow a very complete game!
PS: Just so you know in the future : X+Z isn't a internationally ergonomic choice, in EU many countries don't use QWERY keyboards (I use qwertz, so have to jump with my little finger.. and that finger is the least agile I have :p)
See: https://en.wikipedia.org/wiki/Keyboard_layout#QWERTY-based_layouts_for_Latin_script