Thank you very much :)
Very valuable feedback. I was thinking about making the bullets bigger, or making the character even slower if you just move the stick gently, but a bit of auto-aim might help too, I'll definitely try that out.
Lagging is a problem even on relatively good hardware when there are a lot of zombies on screen, so I definitely need to optimize some more :D (that's also why there's no webbuild, btw. That was even worse performance-wise).
Glad you liked the game though!