UI nitpicks: If you don't hit the "apply" button in the settings and leave the settings screen, when you come back the values are still what you previously chose, but they haven't been applied. This lead me to believe that the mouse sensitivity option wasn't doing anything. By contrast the "default" button automatically applies everything so I lost my settings when I missclicked it
Game: I like the concept of fast paced levels with the goal of improving your time. I'm not sure I see the point "charge", especially since the levels can be cleared without reloading (with the right gun). I like the varous firing modes but the safety is annoying.
It would be nice to have a time for each available firearm since right now there is no point in using the handguns or shotguns, as they are slower.
I found it hard to find a mouse sensitivity that worked for both hip shooting and aiming down sight, being able to set them to different values would be nice.