2.5D is my favourite! Cool visuals and sound FX! The difficulty is just right in my opinion!
One suggestion: It's hard to know where your front is (which direction you will shoot in) when rotating, so it would be nice to perhaps have like a gun sticking out of the cube or something, as I would often rotate, think I will kill the enemy, only to realize my bullet is going 30 degrees to the left of where I thought it would :D
Overall, very well done on finishing the game in time and submitting, congratz!