Strange idea, boxes falling and shooting buttons... but in the lot of strange ideas, really fun games can turn up and I guess the only way to find out is try. So keep it up! :)
Like grahamster00 I got stuck under boxes. Protected, I just kept on shooting till I got all the badges .. then tried to quit, that's where I discovered the death button! 'R' <- nice one :)
(+also agree with grahamster00, controls should be explained in game - imo, one shouldn't expect everybody to read the description)
One more thing while I'm at it: Plz note that the 'Z' key is not a very international choice. There are many different keyboard layouts used in EU, where the 'Z' key's position changes a lot. For me, it's where the 'Y' key is. Luckily, in this game it's not a problem.
See: https://en.wikipedia.org/wiki/Keyboard_layout#QWERTY-based_layouts_for_Latin_script