Well, others mention it doesn't fit the theme, but i read on the description and play the tutorial, and kind of make some sense. Throw the powerup boxes on the pit to become stronger, kinda stronger together with the boxes...
Anyway, the game is fun, even without that thing. My first play-through was without the powerups, cause i can't grab them with E. But then i saw in the tutorial that you found a bug (guess you run out of time to fix it, that's why u put it there) about pause with the box. So I suppose i paused the game and that's what breaks it.
I play it again with the powerups and it's fun. That wireframe box is the devil! Constant shoot without reloading.. damn! Really hard on small places. But managed to destroy them.
I reach a point when it seems the scene repeats forever. The level 2? (the one in a closed space, with 2 wireframe boxes on the map2) I did it like 4 or 5 times, and it's always the same, so I exit the game.
As I mention earlier, the game is still fun.
Nice work. Congratulations!