For a game called "Fast Clear", it is agonizingly slow. Your avatar moves at a snail's pace, and at the same time, your targeting reticle whips around like it's on cocaine; I think my cm/360 (camera movement rate) is like... 2 on my mouse's lowest DPI setting. I move less than an inch, and my camera whips around like I snapped my neck.
Worse still, it can take anywhere from one to a dozen shots for a target to be destroyed, and it's completely random. In the first maze-like level, I had to get up onto the barrel and unload into the target six times to register a hit; meanwhile, I can shoot at a massive target halfway across the map a single time and get a hit marker. It's wildly inconsistent, and I'm not sure if that's by accident or by design.
Oh, right, and the stairs... could've just been a shallow incline, but no, you modeled every stair such that the player has to spam Jump to ascend to the next floor. My laptop keyboard's already starting to go, and I fear my Spacebar may be next.