Simple Zombie Survival is a free action PC game by developer Omega Play Games. It is a first-person arena shooter adventure wherein players will go up against waves of the undead. It features multiplayer gameplay with up to four players and offers a wide variety of weapons and upgrades to utilize for their runs. 

Zombie defense 

In Simple Zombie Survival, you and three others will fight zombies in wave defense gameplay through multiple rounds to save Earth from their overwhelming invasion. Pick from over 20 unique weapons and master their playstyle as you shoot down the undead in fast-paced combat spread through various map locations around the world, and survive until the end. 

Earn cash each round, and use it to unlock perks and power-ups that change how fights play out in all kinds of ways. Experiment with different combinations to find your preferred playstyle. Do note that the game is still in Early Access, though. Development is still ongoing, and the full version is yet to be completed, so there are still plenty of things to come and change in future updates. 

Fun and promising 

To sum up, if you like zombie shooters and are looking for one that you can enjoy playing with others, Simple Zombie Survival is a solid option you can consider. It's a pretty straightforward experience that focuses on fast-paced, action-packed combat with plenty of weapons and power-ups at your disposal. Hopefully, the full version will be complete soon. Nevertheless, this is worth checking out.