Sure, here's a simple implementation of the game you described. Copy and save the following code in a single HTML file:
To play the game, open the HTML file on your smartphone in a web browser that supports HTML5 canvas, and you'll see a joystick control on the screen. Move the joystick to move the player and avoid the zombies. If a zombie touches the player, the game will reset.
Note that this is a simple implementation that can be expanded upon to add more features, levels, and gameplay elements.