the zombies can spawn on top of you

Great graphics but needs work, @dedelamenace.

As @Tatery1 stated, the zombies can appear right on top of you. The hit box is way too strict missing the enemies even as they close in on you.

Here now, use this function if you like to determine if a shot hits an enemy.

function didhit(shotx,shoty,enemyx,enemyy)
  return abs(shotx-enemyx)<8 and abs(shoty-enemyy)<8
end

Will return TRUE if the shot has hit the enemy.

Thanks @dw817, this was my first school project so a lot of things can be improved. I'll try your function