Loved it! Made a let's play in french and found some things to improve. 

-You should make a start menu screen, a pause menu screen, a death menu screen and an end screen

-When you touch a human, he turns around and shoots you

-When a human sees a mott of blood, he starts to be in attention mode and start looking around for you

-More levels! It was really fun!

Idk if you would listen to a french video, but anyways, I loved your game!