Zombs.io is a real-time strategy (RTS) monster game. It's one of the best free zombie games with a storyline, an excellent art style, and a unique gameplay. You can choose from a wide variety of monsters and battle opponents from all over the world. You can even customize your monsters and use special powers. 

The gameplay is based on survival. You need to eat to survive and grow bigger. You can destroy buildings, trees, and even other players. You can use your special powers to destroy them and gain more food and health. The more food you have, the bigger you will be. 

You can join to one of the most addictive free zombie games with a storyline, an excellent art style, and a unique gameplay.