Ill say exactly what i think of the game
I think this game shows a lot of potencial in it, i checked the other reviews of other players and your answers you said you were amateur, but i dont consider it, i think you have a great potencial to make simple graphics game, big and enjoyable, i think virtual cop is a great game, probably one of the best in newgrounds because of simple 3d,but it doesnt lack in gameplay its pretty good the part of headshot, maybe you could get some sounds from unreal games, where it keeps saying first blood,multi kill,monster kill that kinda stuff then you would add all that to the game making it better in the sounds, maybe try and get extra pistol sounds i dont think its possible but what the hell, try and make a pistol animation too if its possible also, and make it fire,if you can!!
i know a good old game that was based on this maybe it is this game, but try and make this game multiplayer where second player would use arrow keys and maybe another key to shoot and hide, but you would have to change how the boss moved and stuff but maybe that was possible, maybe try and put a little more detail in the whole game, i know the file size will be bigger but maybe you could make it less file size, if this is not possible just make the game as big as you can and never give up because i think you got the potencial to make better games