Press space or click your mouse to shoot an enemy. Wherever your mouse pointer is, is the direction the bullet will go. Don't get destroyed.
Thanks to Sahib_Singh2 for some of the code. Credits to https://cooltext.com/ for the text in the menu screen. The settings work now, but there is only 1: Change BG setting, and sadly, the new zombies and crates aren't out yet, I'm still working on them, but Practice Mode has been added, where the targets don't chase you or deal damage, they help you with aim.