I made some important changes. There's a third weapon to unlock, but there's also a "skill move" system. Do certain things and get a reward. I'd like you to tell me if this enhances the gameplay.
making the bullets move faster, and having a clearer indication of ammo (like maybe a number value).
Different weapons have different bullet speeds. Also, this ammo bar is my second take on the ammo indicator. The first one was just a number value and I found it hard to read during intense slaughter.

To differentiate between a machine gun and a shotgun. Like the ammo, the "box" that the player takes, etc...
That's the point - you never know what's inside the box.
Make a lifebar more visible to the player (like been flashing when your health is low).
It is flashing when your health is low...