I also made some interface improvements, so the mouse scrolling gradually gets to the target position instead of instantly. This also made tearing issues less apparent, and makes the game feel more "solid." Implemented, too, are ammunition consumption and some additional attributes for guns (firing time and spread).
There are still some major bugs on the core gameplay (collision issues) but I'm going to ignore those for now during my quest to improve. Not sure what will come up next -- exam season is in full effect, I just finished my first of four -- but hopefully you will like it.