Thank you so much for the feedback! I had indeed darkened the game up in the late stages of development in an attempt to add some difficulty and play up the aesthetic. I probably took it a bit too far though, so will be decreasing this effect a bit in the next iteration.
You are not the only one who encountered an unwinnable game state due to knocking a can into a place where you cannot shoot it. I'm currently working on removing the restriction to being able to turn left/right so that even if you knock a can into one of the corners on the map, you should still be able to turn around and shoot it. I just need to make sure the portion of the world behind where you spawn is appropriately decorated as right now, it's an empty void.
I'm also experimenting with moving the camera towards/away from the player depending on the direction of their movement. That way if you do need to backtrack, you can at least get a bit more notice before you bump into anything. It's not a full 360 camera (which you are correct that I was trying to avoid as a design choice), but I'm hoping it at least makes backtracking less of a pain.