The idea is very original. I think the windows related mecanics have a lot of potentiel. But they felt a bit underexploited in this game. For example rooms with no doors on some of their sides so the windows need to be moved to access it, or an unkillable monster that travel from window to window and can only be killed by closing the window they are currently in.
The combat gameplay was simple but effective, and had a lot of weapon diversity and bonuses, which is really good for a jam. The only real problem is the fact that aiming is controled by the mouse and the game stops everytime I clicked outside the windows (which happened a lot).
Graphics and audio are both great, especially as you didn't used any premade assets.