CONTROLS:

To move you must shoot your gun in the opposite direction you want to go (press Mouse 1)

You must also watch your bullets, as you can only have 5 at a time (unless...)

You automatically reload when on the ground

To restart, press R

To fullscreen, press the screen icon on the top right

To exit fullscreen, press the X icon on the top right

If you found a secret weapon, just click on it on the UI to change to that weapon (Note that it will start with 0 ammo, so you will have to be on the ground to start using it)