So I gotta say, I really adore what you've done here. Cool setup, satisfying gameplay, great pacing, awesome aesthetics, and really pleasing music.
However.
You completely lost me on this once I hit the section where you have to find gas. The enemies faced there are so absolutely abysmal to fight. They're damage sponges, the player isn't supplied nearly enough weaponry/ammunition, they hit ridiculously hard, and the sound effects they make are ear grating. It just feels like a bizarre spike in difficulty and doesn't match the quality of everything else up unto that point.
I'm sorry if that sounds mean, I really think you're a talented dev and this game is super awesome, but I don't know if I want to continue playing. I've died multiple times to these guys on the easiest difficulty setting, they simply aren't fun to fight at all.