sup, i dont exactly know what you mean by shooting thru walls. The game was meant to simulate a 3d environment, that's why you can go behind certain walls like pillars or bottom of a room. Those areas are meant to be walkable and shootable, the perspective here can be deceiving given its a 2d game.
about the controls, yeah they suck. In fact so much that you can periodically save yourself a copy of the itch.io page when trying to summon a clone and go down at the same time.
cheers, piotrek4!