I think you have a solid ground for this game. I would have enjoyed if there were more types of enemies and bullet patterns. I like that you have implemented that you can see how much ammo and heat (I think?) you have on the crosshair, since that's where you're looking at most of the time. I also enjoyed that you had some storytelling with the objects in your scene.
There are some technical things that needs to be solved for this to get an even better feel, like the main character clipping through some of the walls and not being able to enter all spaces because their hitbox is too big. You might want to make the hitboxes for the walls a bit smaller?