You should pop up the text to "press B to buy" because i never understood how to play until i see the control, but nice game, maybe a little too dark for a wave based game.
The darkness is just a default based on the brightness of my monitor. You can adjust how "dark" it is in the Settings -> Display -> Shadow Opacity menu.
Also, I'm working on adding icons to the screen to indicate what buttons to press to access certain menus.
