WASD to move and clicking will fire. You could just keep your left mouse button pressed and this will make bullets rapid fire. What you have to do in this game is to kill the zombies and reach the purple background. Each time you reach it, it will spawn in a new map. Stand on top of a letter when it spawns in. You will need to collect all of the letters to win the game. Zombies will be killed immediately.
I made this project a happy birthday gift as it features the need for you to collect all the letters of the phrase, "Happy Birthday". I will probably utilize aspects of these projects in my future projects, but for now, this is where I will keep it. Feel free to copy the code and make your character shoot, make the zombies spawn back when they hit the brown, etc. Just don't forget to credit me (; July 21, 2020: V. 1.01: Added a HealthBar and a new Zombie Skin