A difficult game I created a few years ago, ~2012-2015. I recommend turning off the audio, it sounds absolutely awful, it's like a 6 second loop as well.

Zombie Types
Green - Slow, Boring.
Blue - Fast, Cool!
Red - Warps around, Distracting. (Can be disabled on title screen.)
Yellow - Vertical, Vertical!
Gold - Homing, Annoying.

Controls

Arrow Keys - Up for up, Down for down, and Right to go straight.

Z - (When you get the gun) Fire

If you reach an error, just click abort. Not sure what's causing the errors.