You can use any script in this game, but don't use blood effect and weapon models. Blood Effect is sales on Unity Asset Store, and it's not my resource so you could have disadvantage or might be subject to legal regulations. Weapon models are from, I used free models but I'm not sure they can use for commercial purpose.

UnitZ UNET 2.0.1

UNET Multiplayer Survival Game. 

This project provided a useful template and tools to help you create your open world multiplayer game in a few steps. the project includes difference enemies with optimized AI and difference functioning items like Gun , Sword , Grenade , Food and more you can also craft, hunt, or build your base and play around with your friends by drive a Car, This project also ready for a several shooting gameplay styles such as Team / Death match , Co-op Survival Horror , Zombie Swarm , You can create your world, custom your rule and enjoy with your friends. 

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