Cool that you made everything yourself, and the lighting on the bullets looks great!
Some easy wins: the game window is really small for me with no fullscreen button, so I couldn't read the timer. A small pitch variation on the shooting sound would make it less repetitive, and a quick line at the start explaining the goal would help, since the timer ended at different moments each round and I wasn't sure what ended it. For the theme, making the bats only visible in the flashlight could be a cool way to tie it in!
Great job!